digitalmars.D.learn - Safe copy-paste using mixin

drug (5/5) Aug 31 2015 I have code that is being duplicated in several places and I'd like to

drug (2/7) Aug 31 2015 Of course I can just trasnfer these lines below, but the question remain...

Andrea Fontana (23/37) Aug 31 2015 Just create a function that return a string with those three

drug (4/24) Aug 31 2015 As usual in D the answer is simple.)

cym13 (6/40) Aug 31 2015 That's what template mixins are for (although in your example

drug (4/42) Aug 31 2015 According to these sources that I've seen before I can mixin

Andrea Fontana (2/36) Aug 31 2015 Which is the problem in your case?

drug (3/38) Aug 31 2015 No, in my case there is no problem, I'm curious. I guess that string

cym13 (6/48) Aug 31 2015 IMHO they are a hack. That's why they should be used with caution

drug (3/9) Sep 01 2015 I guessed that mixing code instead of strings let compiler checks it

drug <drug2004 bk.ru> writes:

I have code that is being duplicated in several places and I'd like to 
use mixins to simplify code maintenance but I failed to do it. For 
example https://github.com/drug007/hdf5-d-examples/blob/tmp/examples/aux.d

Lines 80-82, 91-93 and 99-101 are identical, how can I use mixin here?
I failed to do it because mixins demand declarations, not just code.

Aug 31 2015

drug <drug2004 bk.ru> writes:

On 31.08.2015 13:35, drug wrote:
 I have code that is being duplicated in several places and I'd like to
 use mixins to simplify code maintenance but I failed to do it. For
 example https://github.com/drug007/hdf5-d-examples/blob/tmp/examples/aux.d

 Lines 80-82, 91-93 and 99-101 are identical, how can I use mixin here?
 I failed to do it because mixins demand declarations, not just code.

Of course I can just trasnfer these lines below, but the question remains.

Aug 31 2015

"Andrea Fontana" <nospam example.com> writes:

On Monday, 31 August 2015 at 10:38:41 UTC, drug wrote:
 On 31.08.2015 13:35, drug wrote:
 I have code that is being duplicated in several places and I'd 
 like to
 use mixins to simplify code maintenance but I failed to do it. 
 For
 example 
 https://github.com/drug007/hdf5-d-examples/blob/tmp/examples/aux.d

 Lines 80-82, 91-93 and 99-101 are identical, how can I use 
 mixin here?
 I failed to do it because mixins demand declarations, not just 
 code.

 Of course I can just trasnfer these lines below, but the 
 question remains.

Just create a function that return a string with those three 
lines and mixin it!

Like:

import std.stdio;

string toMix( string a, string b, string c)
{
	return `string a = "` ~ a ~ `";` ~ `string b = "` ~ b ~ `";` 
`string c = "` ~ c ~ `";`;
}


void main()
{
	
	{
		mixin(toMix("hello", " world", " 1"));
		writeln(a,b,c);
	}
	
	{
		mixin(toMix("hello", " world", " 2"));
		writeln(a,b,c);
	}
}

Aug 31 2015

drug <drug2004 bk.ru> writes:

On 31.08.2015 13:57, Andrea Fontana wrote:
 Just create a function that return a string with those three lines and
 mixin it!

 Like:

 import std.stdio;

 string toMix( string a, string b, string c)
 {
      return `string a = "` ~ a ~ `";` ~ `string b = "` ~ b ~ `";`
 `string c = "` ~ c ~ `";`;
 }


 void main()
 {

      {
          mixin(toMix("hello", " world", " 1"));
          writeln(a,b,c);
      }

      {
          mixin(toMix("hello", " world", " 2"));
          writeln(a,b,c);
      }
 }

As usual in D the answer is simple.)

But sometimes string mixins aren't desired, it would be nice to mixin 
the code, not strings.

Aug 31 2015

"cym13" <cpicard openmailbox.org> writes:

On Monday, 31 August 2015 at 11:06:40 UTC, drug wrote:
 On 31.08.2015 13:57, Andrea Fontana wrote:
 Just create a function that return a string with those three 
 lines and
 mixin it!

 Like:

 import std.stdio;

 string toMix( string a, string b, string c)
 {
      return `string a = "` ~ a ~ `";` ~ `string b = "` ~ b ~ 
 `";`
 `string c = "` ~ c ~ `";`;
 }


 void main()
 {

      {
          mixin(toMix("hello", " world", " 1"));
          writeln(a,b,c);
      }

      {
          mixin(toMix("hello", " world", " 2"));
          writeln(a,b,c);
      }
 }

 As usual in D the answer is simple.)

 But sometimes string mixins aren't desired, it would be nice to 
 mixin the code, not strings.

That's what template mixins are for (although in your example 
string mixins are better suited imho). You may want to have a 
look at 
https://blog.dicebot.lv/posts/2015/08/OOP_composition_with_mixins 
or of course http://dlang.org/template-mixin.html

Aug 31 2015

drug <drug2004 bk.ru> writes:

On 31.08.2015 14:36, cym13 wrote:
 On Monday, 31 August 2015 at 11:06:40 UTC, drug wrote:
 On 31.08.2015 13:57, Andrea Fontana wrote:
 Just create a function that return a string with those three lines and
 mixin it!

 Like:

 import std.stdio;

 string toMix( string a, string b, string c)
 {
      return `string a = "` ~ a ~ `";` ~ `string b = "` ~ b ~ `";`
 `string c = "` ~ c ~ `";`;
 }


 void main()
 {

      {
          mixin(toMix("hello", " world", " 1"));
          writeln(a,b,c);
      }

      {
          mixin(toMix("hello", " world", " 2"));
          writeln(a,b,c);
      }
 }

 As usual in D the answer is simple.)

 But sometimes string mixins aren't desired, it would be nice to mixin
 the code, not strings.

 That's what template mixins are for (although in your example string
 mixins are better suited imho). You may want to have a look at
 https://blog.dicebot.lv/posts/2015/08/OOP_composition_with_mixins or of
 course http://dlang.org/template-mixin.html

According to these sources that I've seen before I can mixin 
declarations, not just arbitrary code. Now I guess it's impossible for 
some reason.

Aug 31 2015

"Andrea Fontana" <nospam example.com> writes:

On Monday, 31 August 2015 at 11:06:40 UTC, drug wrote:
 On 31.08.2015 13:57, Andrea Fontana wrote:
 Just create a function that return a string with those three 
 lines and
 mixin it!

 Like:

 import std.stdio;

 string toMix( string a, string b, string c)
 {
      return `string a = "` ~ a ~ `";` ~ `string b = "` ~ b ~ 
 `";`
 `string c = "` ~ c ~ `";`;
 }


 void main()
 {

      {
          mixin(toMix("hello", " world", " 1"));
          writeln(a,b,c);
      }

      {
          mixin(toMix("hello", " world", " 2"));
          writeln(a,b,c);
      }
 }

 As usual in D the answer is simple.)

 But sometimes string mixins aren't desired, it would be nice to 
 mixin the code, not strings.

Which is the problem in your case?

Aug 31 2015

drug <drug2004 bk.ru> writes:

On 31.08.2015 15:28, Andrea Fontana wrote:
 On Monday, 31 August 2015 at 11:06:40 UTC, drug wrote:
 On 31.08.2015 13:57, Andrea Fontana wrote:
 Just create a function that return a string with those three lines and
 mixin it!

 Like:

 import std.stdio;

 string toMix( string a, string b, string c)
 {
      return `string a = "` ~ a ~ `";` ~ `string b = "` ~ b ~ `";`
 `string c = "` ~ c ~ `";`;
 }


 void main()
 {

      {
          mixin(toMix("hello", " world", " 1"));
          writeln(a,b,c);
      }

      {
          mixin(toMix("hello", " world", " 2"));
          writeln(a,b,c);
      }
 }

 As usual in D the answer is simple.)

 But sometimes string mixins aren't desired, it would be nice to mixin
 the code, not strings.

 Which is the problem in your case?

No, in my case there is no problem, I'm curious. I guess that string 
mixins sometimes may look like a hack.

Aug 31 2015

"cym13" <cpicard openmailbox.org> writes:

On Monday, 31 August 2015 at 12:43:25 UTC, drug wrote:
 On 31.08.2015 15:28, Andrea Fontana wrote:
 On Monday, 31 August 2015 at 11:06:40 UTC, drug wrote:
 On 31.08.2015 13:57, Andrea Fontana wrote:
 Just create a function that return a string with those three 
 lines and
 mixin it!

 Like:

 import std.stdio;

 string toMix( string a, string b, string c)
 {
      return `string a = "` ~ a ~ `";` ~ `string b = "` ~ b ~ 
 `";`
 `string c = "` ~ c ~ `";`;
 }


 void main()
 {

      {
          mixin(toMix("hello", " world", " 1"));
          writeln(a,b,c);
      }

      {
          mixin(toMix("hello", " world", " 2"));
          writeln(a,b,c);
      }
 }

 As usual in D the answer is simple.)

 But sometimes string mixins aren't desired, it would be nice 
 to mixin
 the code, not strings.

 Which is the problem in your case?

 No, in my case there is no problem, I'm curious. I guess that 
 string mixins sometimes may look like a hack.

IMHO they are a hack. That's why they should be used with caution 
(and why using them feels so good ^_^ ). But I don't see how 
mixing arbitrary code instead of string would make them less a 
hack. Template mixin allow only declarations for exactly that 
reason AFAIK.

Aug 31 2015

drug <drug2004 bk.ru> writes:

On 31.08.2015 16:30, cym13 wrote:
 No, in my case there is no problem, I'm curious. I guess that string
 mixins sometimes may look like a hack.

 IMHO they are a hack. That's why they should be used with caution (and
 why using them feels so good ^_^ ). But I don't see how mixing arbitrary
 code instead of string would make them less a hack. Template mixin allow
 only declarations for exactly that reason AFAIK.

I guessed that mixing code instead of strings let compiler checks it 
more strictly. But now I think I was wrong and I'm agree with you.

Sep 01 2015

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digitalmars.D.learn - Safe copy-paste using mixin