Precompile Lambda Expression Tree conversions as constants?
- by Nathan
It is fairly common to take an Expression tree, and convert it to some other form, such as a string representation (for example this question and this question, and I suspect Linq2Sql does something similar).
In many cases, perhaps even most cases, the Expression tree conversion will always be the same, i.e. if I have a function
public string GenerateSomeSql(Expression<Func<TResult, TProperty>> expression)
then any call with the same argument will always return the same result for example:
GenerateSomeSql(x => x.Age) //suppose this will always return "select Age from Person"
GenerateSomeSql(x => x.Ssn) //suppose this will always return "select Ssn from Person"
So, in essence, the function call with a particular argument is really just a constant, except time is wasted at runtime re-computing it continuously.
Assuming, for the sake of argument, that the conversion was sufficiently complex to cause a noticeable performance hit, is there any way to pre-compile the function call into an actual constant?
