Transform a function's body into a string for mixing in

[Emmanuelle]

On Thursday, 20 June 2019 at 20:38:48 UTC, Dennis wrote:
> On Thursday, 20 June 2019 at 19:09:11 UTC, Emmanuelle wrote:
>> Is there any trait or Phobos function for transforming a 
>> function/delegate/lambda/whatever's body into a string 
>> suitable for `mixin(...)`? For example:
>
> See:
> https://forum.dlang.org/post/kozwskltzidfnatbpjgb@forum.dlang.org
>
>> If not, is there any way to do this _without_ using strings?
>
> Depends on what you are trying to achieve with mixing in 
> function body code. If you just want to execute the function 
> code, you can just call it (obviously), so I assume you want 
> dynamic scoping (that global variables are overridden by local 
> variables from the caller) or something?

Yeah, I want to be able to basically use mixin templates but with 
expressions instead, with the code being executed on the scope of 
the caller, not the callee; but it seems that's impossible 
without passing strings. For example, I recently hit an issue 
with closure scoping 
(https://forum.dlang.org/post/rnxebjcfpmyzptpwzyee@forum.dlang.org) that can be worked around by using IIFEs; I thought, hey, maybe I could make a mixin that turns, say, this (taking the example from the post I just linked):

---
((x) => (int i) { nums[x] ~= i; })(x);
---

into this:

---
mixin(capture!(x, (int i) { nums[x] ~= i; });
---

where the variables I need captured go first there (in this case, 
only `x`). Of course, that doesn't work unless I use strings 
everywhere:

---
mixin(capture!("x", q{(int i) { nums[x] ~= i; }});
---

which I find rather ugly and inconvenient.

The technique you linked seems interesting but also loads of work 
so I'll just give up on this idea for now lol. Thanks though!