Is it OK to use dynamic typing to reduce the amount of variables in scope?
- by missingno
Often, when I am initializing something I have to use a temporary variable, for example:
file_str = "path/to/file"
file_file = open(file)
or
regexp_parts = ['foo', 'bar']
regexp = new RegExp( regexp_parts.join('|') )
However, I like to reduce the scope my variables to the smallest scope possible so there is less places where they can be (mis-)used. For example, I try to use for(var i ...) in C++ so the loop variable is confined to the loop body.
In these initialization cases, if I am using a dynamic language, I am then often tempted to reuse the same variable in order to prevent the initial (and now useless) value from being used latter in the function.
file = "path/to/file"
file = open(file)
regexp = ['...', '...']
regexp = new RegExp( regexp.join('|') )
The idea is that by reducing the number of variables in scope I reduce the chances to misuse them. However this sometimes makes the variable names look a little weird, as in the first example, where "file" refers to a "filename".
I think perhaps this would be a non issue if I could use non-nested scopes
begin scope1
filename = ...
begin scope2
file = open(filename)
end scope1
//use file here
//can't use filename on accident
end scope2
but I can't think of any programming language that supports this.
What rules of thumb should I use in this situation?
When is it best to reuse the variable?
When is it best to create an extra variable?
What other ways do we solve this scope problem?
