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• In dependency injection, is there a simple name for the counterpart of the injected object?

  - by kostja

  In tutorials and books, I have never seen a single word describing the object that the injected object is injected into. Instead, other terms are used, like "injection point" which don't denote the object containing the injected object. And nothing I can think of sounds right, except maybe "injection target" - but I have never read it anywhere. Is there a single word or a simple expression for it, or is it like the "He-Who-Must-Not-Be-Named" from a recent fantasy book series?

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• Architecture or Pattern for handling properties with custom setter/getter?

  - by Shelby115

  Current Situation: I'm doing a simple MVC site for keeping journals as a personal project. My concern is I'm trying to keep the interaction between the pages and the classes simplistic. Where I run into issues is the password field. My setter encrypts the password, so the getter retrieves the encrypted password. public class JournalBook { private IEncryptor _encryptor { get; set; } private String _password { get; set; } public Int32 id { get; set; } public String name { get; set; } public String description { get; set; } public String password { get { return this._password; } set { this.setPassword(this._password, value, value); } } public List<Journal> journals { get; set; } public DateTime created { get; set; } public DateTime lastModified { get; set; } public Boolean passwordProtected { get { return this.password != null && this.password != String.Empty; } } ... } I'm currently using model-binding to submit changes or create new JournalBooks (like below). The problem arises that in the code below book.password is always null, I'm pretty sure this is because of the custom setter. [HttpPost] public ActionResult Create(JournalBook book) { // Create the JournalBook if not null. if (book != null) this.JournalBooks.Add(book); return RedirectToAction("Index"); } Question(s): Should I be handling this not in the property's getter/setter? Is there a pattern or architecture that allows for model-binding or another simple method when properties need to have custom getters/setters to manipulate the data? To summarize, how can I handle the password storing with encryption such that I have the following, Robust architecture I don't store the password as plaintext. Submitting a new or modified JournalBook is as easy as default model-binding (or close to it).

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• Plone: Creating new Page fails "AttributeError: 'str' object has no attribute 'dates'"

  - by paskster

  I just installed Plone on my Centos 5.5. I was able login via the admin-account and create new users. But when I try to create a new page I get the following error message: Traceback (innermost last): Module ZPublisher.Publish, line 127, in publish Module ZPublisher.mapply, line 77, in mapply Module ZPublisher.Publish, line 47, in call_object Module Products.CMFPlone.FactoryTool, line 446, in __call__ Module ZPublisher.mapply, line 77, in mapply Module ZPublisher.Publish, line 47, in call_object Module Products.CMFFormController.FSControllerPageTemplate, line 91, in __call__ Module Products.CMFFormController.BaseControllerPageTemplate, line 31, in _call Module Shared.DC.Scripts.Bindings, line 324, in __call__ Module Shared.DC.Scripts.Bindings, line 361, in _bindAndExec Module Products.CMFCore.FSPageTemplate, line 240, in _exec Module Products.CMFCore.FSPageTemplate, line 180, in pt_render Module Products.PageTemplates.PageTemplate, line 80, in pt_render Module zope.pagetemplate.pagetemplate, line 113, in pt_render Warning: Macro expansion failed Warning: <type 'exceptions.KeyError'>: 'macro' Module zope.tal.talinterpreter, line 271, in __call__ Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 888, in do_useMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 888, in do_useMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 954, in do_defineSlot Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 858, in do_defineMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 954, in do_defineSlot Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 946, in do_defineSlot Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 858, in do_defineMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 888, in do_useMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 852, in do_condition Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 954, in do_defineSlot Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 852, in do_condition Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 821, in do_loop_tal Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 522, in do_optTag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 821, in do_loop_tal Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 888, in do_useMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 888, in do_useMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 852, in do_condition Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 852, in do_condition Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 946, in do_defineSlot Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 533, in do_optTag_tal Module zope.tal.talinterpreter, line 518, in do_optTag Module zope.tal.talinterpreter, line 513, in no_tag Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 888, in do_useMacro Module zope.tal.talinterpreter, line 343, in interpret Module zope.tal.talinterpreter, line 583, in do_setLocal_tal Module zope.tales.tales, line 696, in evaluate URL: file:/usr/local/Plone/buildout-cache/eggs/Plone-4.0.2-py2.6.egg/Products/CMFPlone/skins/plone_templates/calendar_macros.pt Line 12, Column 4 Expression: <PythonExpr date_components_support_view.result(inputvalue, 0, starting_year, ending_year, future_years)> Names: {'container': <PloneSite at /reeple>, 'context': <ATDocument at /reeple/portal_factory/Document/document.2010-12-24.9331499294 used for /reeple>, 'default': <object object at 0x2ad1b9a18ae0>, 'here': <ATDocument at /reeple/portal_factory/Document/document.2010-12-24.9331499294 used for /reeple>, 'loop': {u'field': <Products.PageTemplates.Expressions.PathIterator object at 0x1bc9b9d0>, u'fieldset': <Products.PageTemplates.Expressions.PathIterator object at 0x1d396c90>}, 'nothing': None, 'options': {'args': (), 'state': <Products.CMFFormController.ControllerState.ControllerState object at 0x1ccdb2d0>}, 'repeat': <Products.PageTemplates.Expressions.SafeMapping object at 0x1d452ec0>, 'request': <HTTPRequest, URL=http://82.165.145.121:8081/reeple/portal_factory/Document/document.2010-12-24.9331499294/atct_edit>, 'root': <Application at >, 'template': <FSControllerPageTemplate at /reeple/atct_edit used for /reeple/portal_factory/Document/document.2010-12-24.9331499294>, 'traverse_subpath': [], 'user': <PloneUser 'pascalklein'>} Module Products.PageTemplates.ZRPythonExpr, line 49, in __call__ __traceback_info__: date_components_support_view.result(inputvalue, 0, starting_year, ending_year, future_years) Module PythonExpr, line 1, in <expression> Module plone.app.form.widgets.datecomponents, line 50, in result AttributeError: 'str' object has no attribute 'dates' Any suggestions? CentOS 5.5 has the Python Version 2.4. So I'm not sure if that causes the issue.

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• SQL Server: SELECT rows with MAX(Column A), MAX(Column B), DISTINCT by related columns

  - by z531

  Scenario: Table A MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/1/2010, 'Fred', null, null 2, 1/2/2010, 'Barney', 'Mr. Slate', 1/7/2010 3, 1/3/2010, 'Noname', null, null Table B MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/3/2010, 'Wilma', 'The Great Kazoo', 1/5/2010 2, 1/4/2010, 'Betty', 'Dino', 1/4/2010 Table C MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/5/2010, 'Pebbles', null, null 2, 1/6/2010, 'BamBam', null, null Table D MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/2/2010, 'Noname', null, null 3, 1/4/2010, 'Wilma', null, null I need to return the max added date and corresponding user, and max updated date and corresponding user for each distinct record when tables A,B,C&D are UNION'ed, i.e.: 1, 1/5/2010, 'Pebbles', 'The Great Kazoo', 1/5/2010 2, 1/6/2010, 'BamBam', 'Mr. Slate', 1/7/2010 3, 1/4/2010, 'Wilma', null, null I know how to do this with one date/user per row, but with two is beyond me. DBMS is SQL Server 2005. T-SQL solution preferred. Thanks in advance, Dave

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• intersection curve of 3D mesh object and 2D plane

  - by Terry

  Hi All, I need a computer graphics book that gives the intersection curve of 3D mesh object and 2D plane. Could you advise me a book. Regards Terry

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• sql: Group by x,y,z; return grouped by x,y with lowest f(z)

  - by Sai Emrys

  This is for http://cssfingerprint.com I collect timing stats about how fast the different methods I use perform on different browsers, etc., so that I can optimize the scraping speed. Separately, I have a report about what each method returns for a handful of URLs with known-correct values, so that I can tell which methods are bogus on which browsers. (Each is different, alas.) The related tables look like this: CREATE TABLE `browser_tests` ( `id` int(11) NOT NULL AUTO_INCREMENT, `bogus` tinyint(1) DEFAULT NULL, `result` tinyint(1) DEFAULT NULL, `method` varchar(255) DEFAULT NULL, `url` varchar(255) DEFAULT NULL, `os` varchar(255) DEFAULT NULL, `browser` varchar(255) DEFAULT NULL, `version` varchar(255) DEFAULT NULL, `created_at` datetime DEFAULT NULL, `updated_at` datetime DEFAULT NULL, `user_agent` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=33784 DEFAULT CHARSET=latin1 CREATE TABLE `method_timings` ( `id` int(11) NOT NULL AUTO_INCREMENT, `method` varchar(255) DEFAULT NULL, `batch_size` int(11) DEFAULT NULL, `timing` int(11) DEFAULT NULL, `os` varchar(255) DEFAULT NULL, `browser` varchar(255) DEFAULT NULL, `version` varchar(255) DEFAULT NULL, `user_agent` varchar(255) DEFAULT NULL, `created_at` datetime DEFAULT NULL, `updated_at` datetime DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=28849 DEFAULT CHARSET=latin1 (user_agent is broken down pre-insert into browser, version, and os from a small list of recognized values using regex; I keep the original user-agent string just in case.) I have a query like this that tells me the average timing for every non-bogus browser / version / method tuple: select c, avg(bogus) as bog, timing, method, browser, version from browser_tests as b inner join ( select count(*) as c, round(avg(timing)) as timing, method, browser, version from method_timings group by browser, version, method having c > 10 order by browser, version, timing ) as t using (browser, version, method) group by browser, version, method having bog < 1 order by browser, version, timing; Which returns something like: c bog tim method browser version 88 0.8333 184 reuse_insert Chrome 4.0.249.89 18 0.0000 238 mass_insert_width Chrome 4.0.249.89 70 0.0400 246 mass_insert Chrome 4.0.249.89 70 0.0400 327 mass_noinsert Chrome 4.0.249.89 88 0.0556 367 reuse_reinsert Chrome 4.0.249.89 88 0.0556 383 jquery Chrome 4.0.249.89 88 0.0556 863 full_reinsert Chrome 4.0.249.89 187 0.0000 105 jquery Chrome 5.0.307.11 187 0.8806 109 reuse_insert Chrome 5.0.307.11 123 0.0000 110 mass_insert_width Chrome 5.0.307.11 176 0.0000 231 mass_noinsert Chrome 5.0.307.11 176 0.0000 237 mass_insert Chrome 5.0.307.11 187 0.0000 314 reuse_reinsert Chrome 5.0.307.11 187 0.0000 372 full_reinsert Chrome 5.0.307.11 12 0.7500 82 reuse_insert Chrome 5.0.335.0 12 0.2500 102 jquery Chrome 5.0.335.0 [...] I want to modify this query to return only the browser/version/method with the lowest timing - i.e. something like: 88 0.8333 184 reuse_insert Chrome 4.0.249.89 187 0.0000 105 jquery Chrome 5.0.307.11 12 0.7500 82 reuse_insert Chrome 5.0.335.0 [...] How can I do this, while still returning the method that goes with that lowest timing? I could filter it app-side, but I'd rather do this in mysql since it'd work better with my caching.

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• Selecting which object to align to in Powerpoint 2007

  - by Ash

  When doing an alignment in Powerpoint 2007 (say, Align Center), is there any way to select which object will be aligned to? It seems to pick one of the objects, but I'm not sure how it decides which one to pick and how to change it. Order of selection and front/back ordering seems to have no effect. Anyone have any ideas?

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• How to access the subject of a compose mail item in Outlook

  - by vwfreak034

  In Outlook, I can set the subject for a new message (when composing a new mail message), but I want to prepend text. So I need to get the subject first, and then set it. Outlook.Application application = Globals.ThisAddIn.Application; Outlook.Inspector inspector = application.ActiveInspector(); Outlook.MailItem myMailItem = (Outlook.MailItem)inspector.CurrentItem; if (myMailItem != null && !string.IsNullOrEmpty(myMailItem.Subject)) { myMailItem.Subject = "Following up on your order"; } This code works on replies, but not for new messages, because in that case, myMailItem is null.

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• Python - Converting CSV to Objects - Code Design

  - by victorhooi

  Hi, I have a small script we're using to read in a CSV file containing employees, and perform some basic manipulations on that data. We read in the data (import_gd_dump), and create an Employees object, containing a list of Employee objects (maybe I should think of a better naming convention...lol). We then call clean_all_phone_numbers() on Employees, which calls clean_phone_number() on each Employee, as well as lookup_all_supervisors(), on Employees. import csv import re import sys #class CSVLoader: # """Virtual class to assist with loading in CSV files.""" # def import_gd_dump(self, input_file='Gp Directory 20100331 original.csv'): # gd_extract = csv.DictReader(open(input_file), dialect='excel') # employees = [] # for row in gd_extract: # curr_employee = Employee(row) # employees.append(curr_employee) # return employees # #self.employees = {row['dbdirid']:row for row in gd_extract} # Previously, this was inside a (virtual) class called "CSVLoader". # However, according to here (http://tomayko.com/writings/the-static-method-thing) - the idiomatic way of doing this in Python is not with a class-fucntion but with a module-level function def import_gd_dump(input_file='Gp Directory 20100331 original.csv'): """Return a list ('employee') of dict objects, taken from a Group Directory CSV file.""" gd_extract = csv.DictReader(open(input_file), dialect='excel') employees = [] for row in gd_extract: employees.append(row) return employees def write_gd_formatted(employees_dict, output_file="gd_formatted.csv"): """Read in an Employees() object, and write out each Employee() inside this to a CSV file""" gd_output_fieldnames = ('hrid', 'mail', 'givenName', 'sn', 'dbcostcenter', 'dbdirid', 'hrreportsto', 'PHFull', 'PHFull_message', 'SupervisorEmail', 'SupervisorFirstName', 'SupervisorSurname') try: gd_formatted = csv.DictWriter(open(output_file, 'w', newline=''), fieldnames=gd_output_fieldnames, extrasaction='ignore', dialect='excel') except IOError: print('Unable to open file, IO error (Is it locked?)') sys.exit(1) headers = {n:n for n in gd_output_fieldnames} gd_formatted.writerow(headers) for employee in employees_dict.employee_list: # We're using the employee object's inbuilt __dict__ attribute - hmm, is this good practice? gd_formatted.writerow(employee.__dict__) class Employee: """An Employee in the system, with employee attributes (name, email, cost-centre etc.)""" def __init__(self, employee_attributes): """We use the Employee constructor to convert a dictionary into instance attributes.""" for k, v in employee_attributes.items(): setattr(self, k, v) def clean_phone_number(self): """Perform some rudimentary checks and corrections, to make sure numbers are in the right format. Numbers should be in the form 0XYYYYYYYY, where X is the area code, and Y is the local number.""" if self.telephoneNumber is None or self.telephoneNumber == '': return '', 'Missing phone number.' else: standard_format = re.compile(r'^\+(?P<intl_prefix>\d{2})\((?P<area_code>\d)\)(?P<local_first_half>\d{4})-(?P<local_second_half>\d{4})') extra_zero = re.compile(r'^\+(?P<intl_prefix>\d{2})\(0(?P<area_code>\d)\)(?P<local_first_half>\d{4})-(?P<local_second_half>\d{4})') missing_hyphen = re.compile(r'^\+(?P<intl_prefix>\d{2})\(0(?P<area_code>\d)\)(?P<local_first_half>\d{4})(?P<local_second_half>\d{4})') if standard_format.search(self.telephoneNumber): result = standard_format.search(self.telephoneNumber) return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), '' elif extra_zero.search(self.telephoneNumber): result = extra_zero.search(self.telephoneNumber) return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), 'Extra zero in area code - ask user to remediate. ' elif missing_hyphen.search(self.telephoneNumber): result = missing_hyphen.search(self.telephoneNumber) return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), 'Missing hyphen in local component - ask user to remediate. ' else: return '', "Number didn't match recognised format. Original text is: " + self.telephoneNumber class Employees: def __init__(self, import_list): self.employee_list = [] for employee in import_list: self.employee_list.append(Employee(employee)) def clean_all_phone_numbers(self): for employee in self.employee_list: #Should we just set this directly in Employee.clean_phone_number() instead? employee.PHFull, employee.PHFull_message = employee.clean_phone_number() # Hmm, the search is O(n^2) - there's probably a better way of doing this search? def lookup_all_supervisors(self): for employee in self.employee_list: if employee.hrreportsto is not None and employee.hrreportsto != '': for supervisor in self.employee_list: if supervisor.hrid == employee.hrreportsto: (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = supervisor.mail, supervisor.givenName, supervisor.sn break else: (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = ('Supervisor not found.', 'Supervisor not found.', 'Supervisor not found.') else: (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = ('Supervisor not set.', 'Supervisor not set.', 'Supervisor not set.') #Is thre a more pythonic way of doing this? def print_employees(self): for employee in self.employee_list: print(employee.__dict__) if __name__ == '__main__': db_employees = Employees(import_gd_dump()) db_employees.clean_all_phone_numbers() db_employees.lookup_all_supervisors() #db_employees.print_employees() write_gd_formatted(db_employees) Firstly, my preamble question is, can you see anything inherently wrong with the above, from either a class design or Python point-of-view? Is the logic/design sound? Anyhow, to the specifics: The Employees object has a method, clean_all_phone_numbers(), which calls clean_phone_number() on each Employee object inside it. Is this bad design? If so, why? Also, is the way I'm calling lookup_all_supervisors() bad? Originally, I wrapped the clean_phone_number() and lookup_supervisor() method in a single function, with a single for-loop inside it. clean_phone_number is O(n), I believe, lookup_supervisor is O(n^2) - is it ok splitting it into two loops like this? In clean_all_phone_numbers(), I'm looping on the Employee objects, and settings their values using return/assignment - should I be setting this inside clean_phone_number() itself? There's also a few things that I'm sorted of hacked out, not sure if they're bad practice - e.g. print_employee() and gd_formatted() both use __dict__, and the constructor for Employee uses setattr() to convert a dictionary into instance attributes. I'd value any thoughts at all. If you think the questions are too broad, let me know and I can repost as several split up (I just didn't want to pollute the boards with multiple similar questions, and the three questions are more or less fairly tightly related). Cheers, Victor

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• How To Initialize Object Which May Be Used In Catch Clause?

  - by Onorio Catenacci

  I've seen this sort of pattern in code before: //pseudo C# code var exInfo = null; //Line A try { var p = SomeProperty; //Line B exInfo = new ExceptionMessage("The property was " + p); //Line C } catch(Exception ex) { exInfo.SomeOtherProperty = SomeOtherValue; //Line D } Usually the code is structured in this fashion because exInfo has to be visible outside of the try clause. The problem is that if an exception occurs on Line B, then exInfo will be null at Line D. The issue arises when something happens on Line B that must occur before exInfo is constructed. But if I set exInfo to a new Object at line A then memory may get leaked at Line C (due to "new"-ing the object there). Is there a better pattern for handling this sort of code? Is there a name for this sort of initialization pattern? By the way I know I could check for exInfo == null before line D but that seems a bit clumsy and I'm looking for a better approach.

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• N-tier Repository POCOs - Aggregates?

  - by Sam

  Assume the following simple POCOs, Country and State: public partial class Country { public Country() { States = new List<State>(); } public virtual int CountryId { get; set; } public virtual string Name { get; set; } public virtual string CountryCode { get; set; } public virtual ICollection<State> States { get; set; } } public partial class State { public virtual int StateId { get; set; } public virtual int CountryId { get; set; } public virtual Country Country { get; set; } public virtual string Name { get; set; } public virtual string Abbreviation { get; set; } } Now assume I have a simple respository that looks something like this: public partial class CountryRepository : IDisposable { protected internal IDatabase _db; public CountryRepository() { _db = new Database(System.Configuration.ConfigurationManager.AppSettings["DbConnName"]); } public IEnumerable<Country> GetAll() { return _db.Query<Country>("SELECT * FROM Countries ORDER BY Name", null); } public Country Get(object id) { return _db.SingleById(id); } public void Add(Country c) { _db.Insert(c); } /* ...And So On... */ } Typically in my UI I do not display all of the children (states), but I do display an aggregate count. So my country list view model might look like this: public partial class CountryListVM { [Key] public int CountryId { get; set; } public string Name { get; set; } public string CountryCode { get; set; } public int StateCount { get; set; } } When I'm using the underlying data provider (Entity Framework, NHibernate, PetaPoco, etc) directly in my UI layer, I can easily do something like this: IList<CountryListVM> list = db.Countries .OrderBy(c => c.Name) .Select(c => new CountryListVM() { CountryId = c.CountryId, Name = c.Name, CountryCode = c.CountryCode, StateCount = c.States.Count }) .ToList(); But when I'm using a repository or service pattern, I abstract away direct access to the data layer. It seems as though my options are to: Return the Country with a populated States collection, then map over in the UI layer. The downside to this approach is that I'm returning a lot more data than is actually needed. -or- Put all my view models into my Common dll library (as opposed to having them in the Models directory in my MVC app) and expand my repository to return specific view models instead of just the domain pocos. The downside to this approach is that I'm leaking UI specific stuff (MVC data validation annotations) into my previously clean POCOs. -or- Are there other options? How are you handling these types of things?

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• Problems getting foreign keys working in MySQL

  - by thehuby

  I've been trying to get a delete to cascade and it just doesn't seem to work. I'm sure I am missing something obvious, can anyone help me find it? I would expect a delete on the 'articles' table to trigger a delete on the corresponding rows in the 'article_section_lt' table. CREATE TABLE articles ( id INTEGER UNSIGNED PRIMARY KEY AUTO_INCREMENT, url_stub VARCHAR(255) NOT NULL UNIQUE, h1 VARCHAR(60) NOT NULL UNIQUE, title VARCHAR(60) NOT NULL, description VARCHAR(150) NOT NULL, summary VARCHAR(150) NOT NULL DEFAULT "", html_content TEXT, date DATE NOT NULL, updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP )ENGINE=INNODB; CREATE TABLE article_sections ( /* blog, news etc */ id INTEGER UNSIGNED PRIMARY KEY AUTO_INCREMENT, url_stub VARCHAR(255) NOT NULL UNIQUE, h1 VARCHAR(60) NOT NULL, title VARCHAR(60) NOT NULL, description VARCHAR(150) NOT NULL, summary VARCHAR(150) NOT NULL DEFAULT "", html_content TEXT NOT NULL DEFAULT "" )ENGINE=INNODB; CREATE TABLE article_section_lt ( fk_article_id INTEGER UNSIGNED NOT NULL REFERENCES articles(id) ON DELETE CASCADE, fk_article_section_id INTEGER UNSIGNED NOT NULL )ENGINE=INNODB;

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• Sorting/Paginating/Filtering Complex Multi-AR Object Tables in Rails

  - by Matt Rogish

  I have a complex table pulled from a multi-ActiveRecord object array. This listing is a combined display of all of a particular user's "favorite" items (songs, messages, blog postings, whatever). Each of these items is a full-fledged AR object. My goal is to present the user with a simplified search, sort, and pagination interface. The user need not know that the Song has a singer, and that the Message has an author -- to the end user both entries in the table will be displayed as "User". Thus, the search box will simply be a dropdown list asking them which to search on (User name, created at, etc.). Internally, I would need to convert that to the appropriate object search, combine the results, and display. I can, separately, do pagination (mislav will_paginate), sorting, and filtering, but together I'm having some problems combining them. For example, if I paginate the combined list of items, the pagination plugin handles it just fine. It is not efficient since the pagination is happening in the app vs. the DB, but let's assume the intended use-case would indicate the vast majority of the users will have less than 30 favorited items and all other behavior, server capabilities, etc. indicates this will not be a bottleneck. However, if I wish to sort the list I cannot sort it via the pagination plugin because it relies on the assumption that the result set is derived from a single SQL query, and also that the field name is consistent throughout. Thus, I must sort the merged array via ruby, e.g. @items.sort_by{ |i| i.whatever } But, since the items do not share common names, I must first interrogate the object and then call the correct sort by. For example, if the user wishes to sort by user name, if the sorted object is a message, I sort by author but if the object is a song, I sort by singer. This is all very gross and feels quite un-ruby-like. This same problem comes into play with the filter. If the user filters on the "parent item" (the message's thread, the song's album), I must translate that to the appropriate collection object method. Also gross. This is not the exact set-up but is close enough. Note that this is a legacy app so changing it is quite difficult, although not impossible. Also, yes there is some DRY that can be done, but don't focus on the style or elegance of the following code. Style/elegance of the SOLUTION is important, however! :D models: class User < ActiveRecord::Base ... has_and_belongs_to_many :favorite_messages, :class_name => "Message" has_and_belongs_to_many :favorite_songs, :class_name => "Song" has_many :authored_messages, :class_name => "Message" has_many :sung_songs, :class_name => "Song" end class Message < ActiveRecord::Base has_and_belongs_to_many :favorite_messages belongs_to :author, :class_name => "User" belongs_to :thread end class Song < ActiveRecord::Base has_and_belongs_to_many :favorite_songs belongs_to :singer, :class_name => "User" belongs_to :album end controller: def show u = User.find 123 @items = Array.new @items << u.favorite_messages @items << u.favorite_songs # etc. etc. @items.flatten! @items = @items.sort_by{ |i| i.created_at } @items = @items.paginate :page => params[:page], :per_page => 20 end def search # Assume user is searching for username like 'Bob' u = User.find 123 @items = Array.new @items << u.favorite_messages.find( :all, :conditions => "LOWER( author ) LIKE LOWER('%bob%')" ) @items << u.favorite_songs.find( :all, :conditions => "LOWER( singer ) LIKE ... " ) # etc. etc. @items.flatten! @items = @items.sort_by{ |i| determine appropriate sorting based on user selection } @items = @items.paginate :page => params[:page], :per_page => 20 end view: #index.html.erb ... <table> <tr> <th>Title (sort ASC/DESC links)</th> <th>Created By (sort ASC/DESC links))</th> <th>Collection Title (sort ASC/DESC links)</th> <th>Created At (sort ASC/DESC links)</th> </tr> <% @items.each |item| do %> <%= render { :partial => "message", :locals => item } if item.is_a? Message %> <%= render { :partial => "song", :locals => item } if item.is_a? Song %> <%end%> ... </table> #message.html.erb # shorthand, not real ruby print out message title, author name, thread title, message created at #song.html.erb # shorthand print out song title, singer name, album title, song created at

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• Understanding Domain Driven Design

  - by Nihilist

  Hi I have been trying to understand DDD for few weeks now. Its very confusing. I dont understand how I organise my projects. I have lot of questions on UnitOfWork, Repository, Associations and the list goes on... Lets take a simple example. Album and Tracks. Album: AlbumId, Name, ListOf Tracks Tracks: TrackId, Name Question1: Should i expose Tracks as a IList/IEnumerabe property on Album ? If that how do i add an album ? OR should i expose a ReadOnlyCollection of Tracks and expose a AddTrack method? Question2: How do i load Tracks for Album [assuming lazy loading]? should the getter check for null and then use a repository to load the tracks if need be? Question3: How do we organise the assemblies. Like what does each assembly have? Model.dll - does it only have the domain entities? Where do the repositories go? Interfaces and implementations both. Can i define IAlbumRepository in Model.dll? Infrastructure.dll : what shold this have? Question4: Where is unit of work defined? How do repository and unit of work communicate? [ or should they ] for example. if i need to add multiple tracks to album, again should this be defined as AddTrack on Album OR should there a method in the repository? Regardless of where the method is, how do I implement unit of work here? Question5: Should the UI use Infrastructure..dll or should there be ServiceLayer? Do my quesitons make sense? Regards

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• Advice on Factory Method

  - by heath

  Using php 5.2, I'm trying to use a factory to return a service to the controller. My request uri would be of the format www.mydomain.com/service/method/param1/param2/etc. My controller would then call a service factory using the token sent in the uri. From what I've seen, there are two main routes I could go with my factory. Single method: class ServiceFactory { public static function getInstance($token) { switch($token) { case 'location': return new StaticPageTemplateService('location'); break; case 'product': return new DynamicPageTemplateService('product'); break; case 'user' return new UserService(); break; default: return new StaticPageTemplateService($token); } } } or multiple methods: class ServiceFactory { public static function getLocationService() { return new StaticPageTemplateService('location'); } public static function getProductService() { return new DynamicPageTemplateService('product'); } public static function getUserService() { return new UserService(); } public static function getDefaultService($token) { return new StaticPageTemplateService($token); } } So, given this, I will have a handful of generic services in which I will pass that token (for example, StaticPageTemplateService and DynamicPageTemplateService) that will probably implement another factory method just like this to grab templates, domain objects, etc. And some that will be specific services (for example, UserService) which will be 1:1 to that token and not reused. So, this seems to be an ok approach (please give suggestions if it is not) for a small amount of services. But what about when, over time and my site grows, I end up with 100s of possibilities. This no longer seems like a good approach. Am I just way off to begin with or is there another design pattern that would be a better fit? Thanks. UPDATE: @JSprang - the token is actually sent in the uri like mydomain.com/location would want a service specific to loction and mydomain.com/news would want a service specific to news. Now, for a lot of these, the service will be generic. For instance, a lot of pages will call a StaticTemplatePageService in which the token is passed in to the service. That service in turn will grab the "location" template or "links" template and just spit it back out. Some will need DynamicTemplatePageService in which the token gets passed in, like "news" and that service will grab a NewsDomainObject, determine how to present it and spit that back out. Others, like "user" will be specific to a UserService in which it will have methods like Login, Logout, etc. So basically, the token will be used to determine which service is needed AND if it is generic service, that token will be passed to that service. Maybe token isn't the correct terminology but I hope you get the purpose. I wanted to use the factory so I can easily swap out which Service I need in case my needs change. I just worry that after the site grows larger (both pages and functionality) that the factory will become rather bloated. But I'm starting to feel like I just can't get away from storing the mappings in an array (like Stephen's solution). That just doesn't feel OOP to me and I was hoping to find something more elegant.

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• Supporting more than one codebase in ANSI-C

  - by Ilker Murat Karakas

  I am working on a project, with an associated Ansi-C code base. (let me call this the 'main' codebase). I now am confronted with a typical problem (stated below), which I believe I would be able to solve much easily if I had an object-oriented language at hand. The problem is this: I will have to start more than one codebases; i.e. I will have to start supporting a parallel codebase (even maybe more in the future). The initial codebases for all the new (i.e. parallel) codebases will initially be identical as the old (i.e. 'main') codebase. As we are talking about the 'C' language, I have till now been thinking of adding '#ifdef' statements to code, and writing the branch-spacific code inside those 'ifdef' blocks. Hoping that I made the problem clear (enough!), I would like to hear thoughts on clever patterns that would help me handle this problem elegantly in Ansi C. Cheers

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• Django Comments and Users integration

  - by Patrick

  Hi folks, I am new to django. I am trying to use django.contrib.comments, I saw the table in the database like this, but how can I integrate it with user_id, user_photos, user_name, user_email....and those things with the django commenting system? I also tried to use thread-comments, but I can't configure it properly, is the django threadedcomments table similar to following ? Please let me know if any of you have done this before....all I need is a user login, and post comments, and then show list of comments with users' profile photos and username, as well as there comments. I think shouldn't be that hard. Thank you very much again. +-----------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | content_type_id | int(11) | NO | MUL | NULL | | | object_pk | longtext | NO | | NULL | | | site_id | int(11) | NO | MUL | NULL | | | user_id | int(11) | YES | MUL | NULL | | | user_name | varchar(50) | NO | | NULL | | | user_email | varchar(75) | NO | | NULL | | | user_url | varchar(200) | NO | | NULL | | | comment | longtext | NO | | NULL | | | submit_date | datetime | NO | | NULL | | | ip_address | char(15) | YES | | NULL | | | is_public | tinyint(1) | NO | | NULL | | | is_removed | tinyint(1) | NO | | NULL | | +-----------------+--------------+------+-----+---------+----------------+

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• why is there extra using where in execution plan of query

  - by user366534

  I see plan of query: EXPLAIN SELECT * FROM `subscribers` WHERE state =4 AND date_added < '2010-12-23 11:47:45' It shows: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subscribers range state_date_added state_date_added 9 NULL 8 Using where Here is indexes of table: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment subscribers 0 PRIMARY 1 subscriber_id A 382039 NULL NULL BTREE subscribers 0 email_list_id 1 email_address A 191019 NULL NULL BTREE subscribers 0 email_list_id 2 list_id A 382039 NULL NULL BTREE subscribers 1 FK_list_id 1 list_id A 10 NULL NULL BTREE subscribers 1 state_date_added 1 state A 12 NULL NULL BTREE subscribers 1 state_date_added 2 date_added A 8128 NULL NULL BTREE The last two lines describes index what is supposed for the query. Why is there in extra column using where? Even If I fetch only state and date_added column, it has in extra column: Using where; Using index. I understand why it has using index, but I don't understand Using where here.

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• How to best propagate changes upwards a hierarchical structure for binding?

  - by H.B.

  If i have a folder-like structure that uses the composite design pattern and i bind the root folder to a TreeView. It would be quite useful if i can display certain properties that are being accumulated from the folder's contents. The question is, how do i best inform the folder that changes occurred in a child-element so that the accumulative properties get updated? The context in which i need this is a small RSS-FeedReader i am trying to make. This are the most important objects and aspects of my model: Composite interface: public interface IFeedComposite : INotifyPropertyChanged { string Title { get; set; } int UnreadFeedItemsCount { get; } ObservableCollection<FeedItem> FeedItems { get; } } FeedComposite (aka Folder) public class FeedComposite : BindableObject, IFeedComposite { private string title = ""; public string Title { get { return title; } set { title = value; NotifyPropertyChanged("Title"); } } private ObservableCollection<IFeedComposite> children = new ObservableCollection<IFeedComposite>(); public ObservableCollection<IFeedComposite> Children { get { return children; } set { children.Clear(); foreach (IFeedComposite item in value) { children.Add(item); } NotifyPropertyChanged("Children"); } } public FeedComposite() { } public FeedComposite(string title) { Title = title; } public ObservableCollection<FeedItem> FeedItems { get { ObservableCollection<FeedItem> feedItems = new ObservableCollection<FeedItem>(); foreach (IFeedComposite child in Children) { foreach (FeedItem item in child.FeedItems) { feedItems.Add(item); } } return feedItems; } } public int UnreadFeedItemsCount { get { return (from i in FeedItems where i.IsUnread select i).Count(); } } Feed: public class Feed : BindableObject, IFeedComposite { private string url = ""; public string Url { get { return url; } set { url = value; NotifyPropertyChanged("Url"); } } ... private ObservableCollection<FeedItem> feedItems = new ObservableCollection<FeedItem>(); public ObservableCollection<FeedItem> FeedItems { get { return feedItems; } set { feedItems.Clear(); foreach (FeedItem item in value) { AddFeedItem(item); } NotifyPropertyChanged("Items"); } } public int UnreadFeedItemsCount { get { return (from i in FeedItems where i.IsUnread select i).Count(); } } public Feed() { } public Feed(string url) { Url = url; } Ok, so here's the thing, if i bind a TextBlock.Text to the UnreadFeedItemsCount there won't be simple notifications when an item is marked unread, so one of my approaches has been to handle the PropertyChanged event of every FeedItem and if the IsUnread-Property is changed i have my Feed make a notification that the property UnreadFeedItemsCount has been changed. With this approach i also need to handle all PropertyChanged events of all Feeds and FeedComposites in Children of FeedComposite, from the sound of it, it should be obvious that this is not such a very good idea, you need to be very careful that items never get added or removed to any collection without having attached the PropertyChanged event handler first and things like that. Also: What do i do with the CollectionChanged-Events which necessarily also cause a change in the sum of the unread items count? Sounds like more event handling fun. It is such a mess, it would be great if anyone has an elegant solution to this since i don't want the feed-reader to end up as awful as my first attempt years ago when i didn't even know about DataBinding...

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• Need MYSQL query for finding lowest score per game player

  - by Chris Barnhill

  I have a game on Facebook called Rails Across Europe. I have a Best Scores page where I show the players with the best 20 scores, which in game terms refers to the lowest winning turn. The problem is that there are a small number of players who play frequently, and their scores dominate the page. I'd like to make the scores page open to more players. So I thought that I could display the single lowest winning turn for each player instead of displaying all of the lowest winning turns for all players. The problem is that the query for this eludes me. So I hope that one of you brilliant StackOverflow folks can help me with this. I have included the relevant MYSQL table schemas below. Here are the the table relationships: player_stats contains statistics for either a game in progress or a completed game. If a game is in progress, winning_turn is zero (which means that games with a winning_turn of zero should not be included in the query). player_stats has a game_player table id reference. game_player contains data describing games currently in progress. game_player has a player table id reference. player contains data describing a person who plays the game. Here's the query I'm currently using: 'SELECT p.fb_user_id, ps.winning_turn, gp.difficulty_level, c.name as city_name, g.name as goods_name, d.cost FROM game_player as gp, player as p, player_stats as ps, demand as d, city as c, goods as g WHERE p.status = "ACTIVE" AND gp.player_id = p.id AND ps.game_player_id = gp.id AND d.id = ps.highest_demand_id AND c.id = d.city_id AND g.id = d.goods_id AND ps.winning_turn > 0 ORDER BY ps.winning_turn ASC, d.cost DESC LIMIT '.$limit.';'; Here are the relevant table schemas: -- -- Table structure for table `player_stats` -- CREATE TABLE IF NOT EXISTS `player_stats` ( `id` int(11) NOT NULL auto_increment, `game_player_id` int(11) NOT NULL, `winning_turn` int(11) NOT NULL, `highest_demand_id` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `game_player_id` (`game_player_id`,`highest_demand_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `game_player` -- CREATE TABLE IF NOT EXISTS `game_player` ( `id` int(10) unsigned NOT NULL auto_increment, `game_id` int(10) unsigned NOT NULL, `player_id` int(10) unsigned NOT NULL, `player_number` int(11) NOT NULL, `funds` int(10) unsigned NOT NULL, `turn` int(10) unsigned NOT NULL, `difficulty_level` enum('STANDARD','ADVANCED','MASTER','ULTIMATE') NOT NULL, `date_last_used` datetime NOT NULL, PRIMARY KEY (`id`), KEY `game_id` (`game_id`,`player_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `player` -- CREATE TABLE IF NOT EXISTS `player` ( `id` int(11) NOT NULL auto_increment, `fb_user_id` char(255) NOT NULL, `fb_proxied_email` text NOT NULL, `first_name` char(255) NOT NULL, `last_name` char(255) NOT NULL, `birthdate` date NOT NULL, `date_registered` datetime NOT NULL, `date_last_logged_in` datetime NOT NULL, `status` enum('ACTIVE','SUSPENDED','CLOSED') NOT NULL, PRIMARY KEY (`id`), KEY `fb_user_id` (`fb_user_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1646 ;

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• Very difficult SQL query

  - by db666

  For the following table definitions: Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------ ENUM NOT NULL NUMBER(4) ENUM should not exceed a length of 4. ENAME CHAR(15) ADDRESS CHAR(25) ADDRESS should not exceed 25 characters. SALARY NUMBER(5) OFFICE CHAR(4) DNUM NOT NULL NUMBER(4) Department which this employee belongs to department Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------- DNUM NOT NULL NUMBER(4) DMGR NOT NULL NUMBER(4) Department manager DNAME NOT NULL CHAR(15) project Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------- PNUM NOT NULL NUMBER(4) PMGR NOT NULL NUMBER(4) Project manager PTITLE NOT NULL CHAR(15) emp_proj Name Null? Type ------------------------------- -------- ---- PNUM NOT NULL NUMBER(4) ENUM NOT NULL NUMBER(4) I have to write SQL query which will find the names of employees who do not share an office but work on the same project, and have different salaries... I've spent last three days trying to figure out something, but no idea as far. I will appreciate any advice.

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• How should I be using IoC in this winform piece of code?

  - by Pure.Krome

  Hi folks, I've got a winform app in visual studio 2010. My app does the following Get a list of files which I need to read the data then insert into a database. For each file, read data and insert into DB. So .. this is the code i have. var list = _repository.GetFileList(); if (list != null) { int i = 0; foreach(var file in list) { i++; var service = new MyService(i, _repository); service.ParseAndSave(); } } So i was hoping to have a new repository for each 'service' i create. Firstly, i'm not sure if I should be using IoC in this case. I believe I should be because then i don't need to tightly couple this winform to a repository. Secondly, I've tried using a Singleton repo, which I don't want and can confirm that it kills that code (crashes with an exception). Some other notes (which shouldn't impact this question) - Using Entity Framework for ASP.NET 4. - Using StructureMap for IoC Can someone help, please?

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• benefit os having a factory for object creation?

  - by ajsie

  im trying to understand the factory design pattern. i dont understand why it's good to have a middleman between the client and the product (object that the client wants). example with no factory: $mac = new Mac(); example with a factory: $appleStore = new AppleStore(); $mac = $appleStore->getProduct('mac'); how does the factory pattern decouple the client from the product? could someone give an example of a future code change that will impact on example 1 negative, but positive in example 2 so i understand the importance of decoupling? thanks

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• C++ inheritance question

  - by user233973

  Hi guys, I have a C++ inheritance related question. I have a set of classes like this (I have not given the complete class structure coz I am lazy :) ). I want to access chiComponent class public methods using com pointer. How should I go about it? Note that I am having to change the object which "com" is pointing to in a lot of places. So I do not think I can have another chiComponent *ccom = <some_cast> com; ccom.chiComponentMethod() How should I go about it? class Component{ }; class chiComponent : public Component { public: void chiComponentMethod() { cout << "Hi! Chi component function called!!"; } } class parent { protected: Component *com; }; class child : public parent{ public: child() { com = new chiComponent(); } } Regards Arun

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• benefit of having a factory for object creation?

  - by ajsie

  I'm trying to understand the factory design pattern. I don't understand why it's good to have a middleman between the client and the product (object that the client wants). example with no factory: $mac = new Mac(); example with a factory: $appleStore = new AppleStore(); $mac = $appleStore->getProduct('mac'); How does the factory pattern decouple the client from the product? Could someone give an example of a future code change that will impact on example 1 negative, but positive in example 2 so I understand the importance of decoupling? Thanks.

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