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digitalmars.D.learn - Playing arround with mixin - alias?

reply Martin Tschierschke <mt smartdolphin.de> writes:
Is it possible to define an alias for something like

mixin(import("local_function_file.d"));

to write only

    use_local_function;

which will be translated to: 
mixin(import("local_function_file.d"));

(this additionally needs the file local_function_file.d in 
source/ +
-J./source as parameter for dmd aka.  dflags "-J./source" in 
dub.sdl)

Regards mt.
Apr 21 2017
next sibling parent reply ketmar <ketmar ketmar.no-ip.org> writes:
Martin Tschierschke wrote:


 Is it possible to define an alias for something like

 mixin(import("local_function_file.d"));

 to write only

     use_local_function;

 which will be translated to: mixin(import("local_function_file.d"));

 (this additionally needs the file local_function_file.d in source/ +
 -J./source as parameter for dmd aka.  dflags "-J./source" in dub.sdl)

 Regards mt.


nope. the best you can get is `mixin use_local_function;`.

i'm assuming that you want your imported function behave like normally 
declared function here.
Apr 21 2017
parent reply biozic <dransic gmail.com> writes:
On Friday, 21 April 2017 at 09:42:33 UTC, ketmar wrote:

 Martin Tschierschke wrote:


 Is it possible to define an alias for something like

 mixin(import("local_function_file.d"));

 to write only

     use_local_function;

 which will be translated to: 
 mixin(import("local_function_file.d"));

 (this additionally needs the file local_function_file.d in 
 source/ +
 -J./source as parameter for dmd aka.  dflags "-J./source" in 
 dub.sdl)

 Regards mt.


 nope. the best you can get is `mixin use_local_function;`.


Would there be an advantage compared to a simple `import 
local_function_file;`?
Apr 21 2017
parent reply ketmar <ketmar ketmar.no-ip.org> writes:
biozic wrote:


 On Friday, 21 April 2017 at 09:42:33 UTC, ketmar wrote:

 Martin Tschierschke wrote:


 Is it possible to define an alias for something like

 mixin(import("local_function_file.d"));

 to write only

     use_local_function;

 which will be translated to: mixin(import("local_function_file.d"));

 (this additionally needs the file local_function_file.d in source/ +
 -J./source as parameter for dmd aka.  dflags "-J./source" in dub.sdl)

 Regards mt.


 nope. the best you can get is `mixin use_local_function;`.


 Would there be an advantage compared to a simple `import 
 local_function_file;`?


i doubt so.
Apr 21 2017
parent reply Martin Tschierschke <mt smartdolphin.de> writes:
On Friday, 21 April 2017 at 10:31:46 UTC, ketmar wrote:

 biozic wrote:


 On Friday, 21 April 2017 at 09:42:33 UTC, ketmar wrote:

 Martin Tschierschke wrote:


 Is it possible to define an alias for something like

 mixin(import("local_function_file.d"));

 to write only

     use_local_function;

 which will be translated to: 
 mixin(import("local_function_file.d"));

 (this additionally needs the file local_function_file.d in 
 source/ +
 -J./source as parameter for dmd aka.  dflags "-J./source" in 
 dub.sdl)

 Regards mt.


 nope. the best you can get is `mixin use_local_function;`.


 Would there be an advantage compared to a simple `import 
 local_function_file;`?


 i doubt so.


So my "solution" on how to get a short cut for using:

writeln(mixin(interp!"${name} you are app. ${age*365} days old"));


// first place in source/exho.d the following code:

auto mixinter(string x)(){return mixin(interp!x);}
auto exho(string x)(){return mixin("writeln("~interp!x~")");}

later compile this with -J./source

source/app.d:

import scriptlike;

auto insert(string name)(){return import(name);}
alias insert!"exho.d" use_exho;



void main()
{
   auto name = userInput!string("Please enter your name");
   auto age = userInput!int("And your age");

//Now you can write in  every scope you need it:
   mixin(use_exho);
   exho!"${name} you are app. ${age*365} days old";

// Which looks little nicer than:
// writeln(mixin(interp!"${name} you are app. ${age*365} days 
old"));

// or if you need the result in a var:

   mixin(use_exho);
   auto var = mixinter!"${name} you are app. ${age*365} days old";

   writeln(var);
}

you may even name the alias just exho and write:

  alias insert!"exho.d" exho;

  mixin(exho);
  exho!"${name} you are app. ${age*365} days old";

(exho was derived from shell echo with mi_x_in)
Apr 21 2017
next sibling parent Martin Tschierschke <mt smartdolphin.de> writes:
On Friday, 21 April 2017 at 11:58:13 UTC, Martin Tschierschke 
wrote:

 On Friday, 21 April 2017 at 10:31:46 UTC, ketmar wrote:

 biozic wrote:




I thought way to complicated:
Just define the string at top:

enum exho="auto mixinter(string x)(){return mixin(interp!x);}
auto exho(string x)(){return 
mixin(\"writeln(\"~interp!x~\")\");}";

Then use:

mixin(exho);
exho!"${name} you are app. ${age*365} days old";

In your scope!
Apr 21 2017
prev sibling parent ketmar <ketmar ketmar.no-ip.org> writes:
Martin Tschierschke wrote:


 i doubt so.


 So my "solution" on how to get a short cut for using:

 writeln(mixin(interp!"${name} you are app. ${age*365} days old"));


..

NEVER. EVER. USE. THE. FOLOWING. IN. YOUR. CODE.
NEVER!!!


import std.stdio;

mixin template usesexpand() {
	import std.format : format;
	string sexpand1(string s) () {
		char[] res;
		res.length = s.length+1024;
		auto rused = res.length;
		auto rpos = rused*0; // i really HAET `size_t`!
		void put(bool escape=true) (const(char)[] s...) {
			foreach (char ch; s) {
				static if (escape) {
					if (ch == '"' || ch == '\\') {
						if (rpos == rused) { rused += 1024; res.length = rused; }
						res[rpos++] = '\\';
					}
				}
				if (rpos == rused) { rused += 1024; res.length = rused; }
				res[rpos++] = ch;
			}
		}

		char[] fmt;
		fmt.length = 256;
		auto fused = fmt.length;
		auto fpos = fused*0; // i really HAET `size_t`!
		void putfmt (const(char)[] s...) {
			foreach (char ch; s) {
				if (fpos == fused) { fused += 1024; fmt.length = fused; }
				fmt[fpos++] = ch;
			}
		}

		putfmt(`format("`);

		auto pos = rpos, epos = rpos;
		pos = 0;
		while (pos < s.length) {
			epos = pos;
			while (epos < s.length && s[epos] != '$') ++epos;
			putfmt("%s");
			put!false(`, "`);
			if (epos+1 >= s.length || s[epos+1] != '{') {
				put(s[pos..epos+1]);
				put!false(`"`);
				pos = epos+1;
				continue;
			}
			put(s[pos..epos]);
			put!false(`"`);
			pos = epos+2;
			while (epos < s.length && s[epos] != '}') ++epos;
			if (epos > pos) {
				putfmt("%s");
				put(`, `);
				put(s[pos..epos]);
			}
			pos = epos+1;
		}
		put(`)`);
		putfmt(`"`);
		return cast(string)fmt[0..fpos]~cast(string)res[0..rpos]; // it is safe to
cast here
	}
	enum sexpandstr(string s) = sexpand1!s;
	enum sexpand(string s) = mixin(sexpand1!s);
	void echo(string s) () { writeln(mixin(sexpand1!s)); }
}

mixin usesexpand;
immutable n = 40;

enum nstr = sexpand!"n is ${n+2}";

void main () {
	mixin usesexpand;
	int a = 42/2;
	echo!"a is ${a*2}"; //writeln(mixin(sexpandstr!"a is ${a*2}"));
	writeln(nstr);
}
Apr 21 2017
prev sibling parent Jonathan M Davis via Digitalmars-d-learn writes:
On Friday, April 21, 2017 09:31:52 Martin Tschierschke via Digitalmars-d-
learn wrote:

 Is it possible to define an alias for something like

 mixin(import("local_function_file.d"));

 to write only

     use_local_function;

 which will be translated to:
 mixin(import("local_function_file.d"));

 (this additionally needs the file local_function_file.d in
 source/ +
 -J./source as parameter for dmd aka.  dflags "-J./source" in
 dub.sdl)

 Regards mt.


You can alias symbols. You can't alias statements, and mixins are always
explicit. Now, you could have a function that returned what you wanted to
mix in so that you just did something like

mixin(use_local_function());

and have use_local_function return whatever code it is you want to mix in,
but you can't just do something like

use_local_function;

and have it work. That would be more like a macro system, and D doesn't have
that. We have string mixins and template mixins, but those are both
explicitly mixed in.

- Jonathan M Davis
Apr 21 2017