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digitalmars.D.learn - Get and add to function body

reply Psychological Cleanup <Help Saving.World> writes:
Is there any way to get the function body of a function, 
delegate, and lambda? I'd also like to extend functions by 
"wrapping" them at compile time generically. For example, I'd 
like to get all the properties of a class and add some code to 
them(sort of like adding a scope, prolog, and/or epilog).

Is any of this possible in D?
Oct 12
next sibling parent Psychological Cleanup <Help Saving.World> writes:
I'd also like to be able to save and store delegates, functions, 
and lambdas. One can't store the pointer to the function because 
it will be invalid, so another means is required, any ideas?

Save("f", (int){ ... }); // Saves to disk
auto f = Load("f"); // Loads from disk
f(3);
Oct 12
prev sibling next sibling parent Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:
On Thursday, October 12, 2017 23:33:39 Psychological Cleanup via 
Digitalmars-d-learn wrote:
 Is there any way to get the function body of a function,
 delegate, and lambda? I'd also like to extend functions by
 "wrapping" them at compile time generically. For example, I'd
 like to get all the properties of a class and add some code to
 them(sort of like adding a scope, prolog, and/or epilog).

 Is any of this possible in D?
You can introspect on symbols in D using __traits, std.traits, and is expressions, and that will allow you to get a function's signature, but it is not possible to get at the function's body. If you want to extend a function by wrapping it, you can certainly generate a wrapper, but that will mean generating a new function that calls the original and not doing anything with the code inside of the original function. You cannot alter existing code when generating code at compile time. You can just examine existing code and generate new code. - Jonathan M Davis
Oct 12
prev sibling parent Steven Schveighoffer <schveiguy yahoo.com> writes:
On 10/12/17 7:33 PM, Psychological Cleanup wrote:
 Is there any way to get the function body of a function, delegate, and 
 lambda? I'd also like to extend functions by "wrapping" them at compile 
 time generically. For example, I'd like to get all the properties of a 
 class and add some code to them(sort of like adding a scope, prolog, 
 and/or epilog).
 
 Is any of this possible in D?
Something like this may work: struct S(T) { private T obj; auto ref opDispatch(string item, Args...)(auto ref Args args) { prolog(); scope(exit) epilog(); mixin("return obj." ~ item ~ args.length == 0 ? ";" : "(args);"); } } Probably needs some more machinery to work for everything. -Steve
Oct 13