Mixin/static if issue

Aug 25, 2021

DLearner

Aug 25, 2021

H. S. Teoh

Aug 25, 2021

DLearner

Aug 25, 2021

jfondren

Aug 25, 2021

DLearner

void main() { import std.stdio; uint TestVar = 5; string mxnWrite_Size_t(string VarName) { static if (typeof(VarName).stringof == "uint") { return `write("` ~ VarName ~ `");`; } else { return `writeln("Apparently TestVar not a uint");`; } } mixin(mxnWrite_Size_t("TestVar")); }

On Wed, Aug 25, 2021 at 10:16:39PM +0000, DLearner via Digitalmars-d-learn wrote: > Please see below: > ``` > void main() { > import std.stdio; > > uint TestVar = 5; > > string mxnWrite_Size_t(string VarName) { ^^^^^^^^^^^^^^ Obviously, VarName is a string. Why would you expect anything else? > static if (typeof(VarName).stringof == "uint") { [[...] I think what you meant to write is: static if (typeof(mixin(VarName)).stringof == "uint") { You want the type of the variable named by VarName, not the type of VarName. T -- Many open minds should be closed for repairs. -- K5 user

void main() { import std.stdio; uint TestVar = 5; string mxnWrite_Size_t(string VarName) { static if (typeof(mixin(VarName)).stringof == "uint") { return `write("` ~ VarName ~ `");`; } else { return `writeln("Apparently TestVar not a uint");`; } } mixin(mxnWrite_Size_t("TestVar")); }

August 25, 2021

Re: Mixin/static if issue

Posted by jfondren
in reply to DLearner

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jfondren

Posted in reply to DLearner

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On Wednesday, 25 August 2021 at 22:52:23 UTC, DLearner wrote:

On Wednesday, 25 August 2021 at 22:33:00 UTC, H. S. Teoh wrote:
[...}

I think what you meant to write is:

   static if (typeof(mixin(VarName)).stringof == "uint") {

You want the type of the variable named by VarName, not the type of VarName.

I understand your reasoning, but:

void main() {
   import std.stdio;

   uint TestVar = 5;

   string mxnWrite_Size_t(string VarName) {

      static if (typeof(mixin(VarName)).stringof == "uint") {

         return `write("` ~ VarName ~ `");`;
      } else {

         return `writeln("Apparently TestVar not a uint");`;	
	  }
   }

   mixin(mxnWrite_Size_t("TestVar"));
}

produced Error: variable VarName cannot be read at compile time

Contrast:

void main() {
   import std.stdio;

   uint TestVar = 5;

   string mxnWrite_Size_t(string VarName)() {

      static if (typeof(mixin(VarName)).stringof == "uint") {

         return `write("` ~ VarName ~ `");`;
      } else {

         return `writeln("Apparently TestVar not a uint");`;	
	  }
   }

   mixin(mxnWrite_Size_t!"TestVar");
}

Output: TestVar

void main() { import std.stdio; uint TestVar = 5; string mxnWrite_Size_t(string VarName)() { static if (typeof(mixin(VarName)).stringof == "uint") { return `write("` ~ VarName ~ `");`; } else { return `writeln("Apparently TestVar not a uint");`; } } mixin(mxnWrite_Size_t!"TestVar"); }

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