• WhatMeWorry (28/28) Oct 25 2022 I'm naturally getting a undefined identifier `s` error in the
• =?UTF-8?Q?Ali_=c3=87ehreli?= (39/41) Oct 25 2022 That can't work because there is no information to infer the type of
• Steven Schveighoffer (16/49) Oct 25 2022 As Ali mentioned, your logic is faulty -- you seem to write that the
• WhatMeWorry (4/4) Oct 25 2022 typeof(screen.output.findSplit("")) s;

WhatMeWorry <kheaser gmail.com> writes:

I'm naturally getting a undefined identifier `s` error in the 
return.  Is there some way to refactor my code?  I tried to 
declare s outside of the else brackets like:

auto screen = executeShell(cmdLine);
auto s;
...
{
     s = screen.output.findSplit("REG_SZ");
}

but that doesn't compile either.



string[] getPath(string cmdLine)
{
     auto screen = executeShell(cmdLine);
	
     if (screen.status != 0)
     {
         writeln(cmdLine, " failed");
     }
     else
     {
         writeln("screen.output = ", screen.output);	
	auto s = screen.output.findSplit("REG_SZ");
         writeln("s[0] = ", s[0]);
         writeln("s[1] = ", s[1]);
         writeln("s[2] = ", s[2]);		
     }
     return (s.split(';'));  // Error: undefined identifier `s`
}

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 10/25/22 15:07, WhatMeWorry wrote:

 auto screen = executeShell(cmdLine);
 auto s;

That can't work because there is no information to infer the type of 
's'. Judging from the return type of getPath, perhaps it's string[]:

string[] s;

This is the question we should answer first: What should happen when 
executeShell fails?

a) It is an error; the program should not continue. Then we can use 
'enforce' (this is my way of coding):

string[] getPath(string cmdLine)
{
     import std.exception : enforce;

     auto screen = executeShell(cmdLine);
     enforce(screen.status == 0, format!"%s failed:\n%s"(cmdLine, 
screen.output));

     writeln("screen.output = ", screen.output);
     auto s = screen.output.findSplit("REG_SZ");
     writeln("s[0] = ", s[0]);
     writeln("s[1] = ", s[1]);
     writeln("s[2] = ", s[2]);

     return (s.split(';'));
}

b) It is not an error; getPath() should return empty array:

string[] getPath(string cmdLine)
{
     string[] result;
     auto screen = executeShell(cmdLine);

     if (screen.status != 0)
     {
         writeln(cmdLine, " failed");
         return null;  // <-- HERE (null converts to any array type)
     }
     else
     {
         // ...
         // Now, 'return' is where 's' is defined:
         return (s.split(';'));
     }
}

Ali

Steven Schveighoffer <schveiguy gmail.com> writes:

On 10/25/22 6:07 PM, WhatMeWorry wrote:
 I'm naturally getting a undefined identifier `s` error in the return.  
 Is there some way to refactor my code?  I tried to declare s outside of 
 the else brackets like:
 
 auto screen = executeShell(cmdLine);
 auto s;
 ...
 {
      s = screen.output.findSplit("REG_SZ");
 }
 
 but that doesn't compile either.
 
 
 
 string[] getPath(string cmdLine)
 {
      auto screen = executeShell(cmdLine);
 
      if (screen.status != 0)
      {
          writeln(cmdLine, " failed");
      }
      else
      {
          writeln("screen.output = ", screen.output);
      auto s = screen.output.findSplit("REG_SZ");
          writeln("s[0] = ", s[0]);
          writeln("s[1] = ", s[1]);
          writeln("s[2] = ", s[2]);
      }
      return (s.split(';'));  // Error: undefined identifier `s`
 }

As Ali mentioned, your logic is faulty -- you seem to write that the 
command failed, but then return something anyway.

Also, you are returning `string[]`, so just declaring `string[] s;` 
should be enough.

However, I did want to mention that if you do want to hoist a difficult 
to name type outside where it is declared with an auto, you can use 
`typeof`:

```d
typeof(screen.output.findSplit("")) s;
```

In this case, it's just `string[]`, but the idea here is you can name a 
type without naming it, by using `typeof` on the expression you would 
have called.

Hope this helps further your D knowledge ;)

-Steve

WhatMeWorry <kheaser gmail.com> writes:

typeof(screen.output.findSplit("")) s;


Perfect. That was the "essence" of my question. But thanks to 
Ali, I don't have to use such esoteric syntax.  D is a wonderful 
language, but I seem to shoot myself in the foot :)