digitalmars.D.learn - Semicolon can be left out after do-while
- Timon Gehr (13/13) Apr 12 2011 I just noticed a little oddity.
- bearophile (4/6) Apr 12 2011 I think Andrei wants (rightly) it to be fixed. So I think it is an imple...
- Steven Schveighoffer (19/33) Apr 12 2011 That looks horrible, reformatted looks even worse:
- spir (8/21) Apr 12 2011 why? I like Go's syntactuc diffs. (except for its "multi-for")
- Steven Schveighoffer (17/35) Apr 12 2011 in Go, this:
- spir (12/48) Apr 12 2011 Oh, that's what you meant! I find this a Good Thing, in that it enforces...
- Steven Schveighoffer (16/73) Apr 13 2011 No, it doesn't enforce anything. The above compiles and runs. What it ...
- Emil Madsen (28/110) Apr 13 2011 Does D throw an error at; if(expression && expression)*; *or only at
- Steven Schveighoffer (10/41) Apr 13 2011 if(condition1 && condition2); is an error.
- Kai Meyer (8/104) Apr 13 2011 I would argue that the more correct way to do this would be to separate
- Emil Madsen (12/161) Apr 13 2011 Well I agree that its more correct for the case posted, but it can just ...
- Andrej Mitrovic (3/5) Apr 13 2011 I've been caught by DMD doing this a couple of times. It saved my
I just noticed a little oddity. Why does this code compile? The equivalent C code is rejected: import std.stdio; //#include <stdio.h> int main(){ int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. (http://www.digitalmars.com/d/2.0/statement.html#DoStatement)
Apr 12 2011
bearophile <bearophileHUGS lycos.com> Timon Gehr:I just noticed a little oddity. Why does this code compile? The equivalent C code is rejected:I think Andrei wants (rightly) it to be fixed. So I think it is an implementation "bug" that will be fixed. Bye, bearophile
Apr 12 2011
On Tue, 12 Apr 2011 14:57:26 -0400, Timon Gehr <timon.gehr gmx.ch> wrote:I just noticed a little oddity. Why does this code compile? The equivalent C code is rejected: import std.stdio; //#include <stdio.h> int main(){ int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. (http://www.digitalmars.com/d/2.0/statement.html#DoStatement)That looks horrible, reformatted looks even worse: int main() { int a,b; do { scanf("%d %d",&a,&b); } // so here is a comment to separate things a bit // // do you think this makes sense?: while(a<b) return 0; } I think the grammar should be changed... This is almost as bad as go's requirement for if statement opening block to be on the same line (would be as bad, but do..while doens't occur a lot). -Steve
Apr 12 2011
On 04/12/2011 09:21 PM, Steven Schveighoffer wrote:int main(){ int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. (http://www.digitalmars.com/d/2.0/statement.html#DoStatement) [...] I think the grammar should be changed...yop!This is almost as bad as go's requirement for if statement opening block to be on the same line...why? I like Go's syntactuc diffs. (except for its "multi-for") denis -- _________________ vita es estrany spir.wikidot.com
Apr 12 2011
On Tue, 12 Apr 2011 17:21:57 -0400, spir <denis.spir gmail.com> wrote:On 04/12/2011 09:21 PM, Steven Schveighoffer wrote:in Go, this: if(x) { gosWriteRoutineThatIDontKnowTheSyntaxOf("hello") } is equivalent to this in D: if(x) { } writeln("hello"); This is frankly unforgivable IMO. Of course it's fixable, but the attitude that "the coder should know better" doesn't really make me comfortable with it. And I hate the "brace on the same line" format (but this of course is not a real argument against it). -Steveint main(){ int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. (http://www.digitalmars.com/d/2.0/statement.html#DoStatement) [...] I think the grammar should be changed...yop!This is almost as bad as go's requirement for if statement opening block to be on the same line...why? I like Go's syntactuc diffs. (except for its "multi-for")
Apr 12 2011
On 04/12/2011 11:51 PM, Steven Schveighoffer wrote:On Tue, 12 Apr 2011 17:21:57 -0400, spir <denis.spir gmail.com> wrote:Oh, that's what you meant! I find this a Good Thing, in that it enforces one bracing style (the right one, that does not eats one more line for just a '{'). About knowing or not about this (non/mis/-)feature, it's written down, and clearly, in all Go docs I've read. And one cannot miss it for very long anyway ;-) Maybe, if not done already, a line starting with an opening brace should generate a parsing error. Denis -- _________________ vita es estrany spir.wikidot.comOn 04/12/2011 09:21 PM, Steven Schveighoffer wrote:in Go, this: if(x) { gosWriteRoutineThatIDontKnowTheSyntaxOf("hello") } is equivalent to this in D: if(x) { } writeln("hello"); This is frankly unforgivable IMO. Of course it's fixable, but the attitude that "the coder should know better" doesn't really make me comfortable with it. And I hate the "brace on the same line" format (but this of course is not a real argument against it).int main(){ int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. (http://www.digitalmars.com/d/2.0/statement.html#DoStatement) [...] I think the grammar should be changed...yop!This is almost as bad as go's requirement for if statement opening block to be on the same line...why? I like Go's syntactuc diffs. (except for its "multi-for")
Apr 12 2011
On Tue, 12 Apr 2011 18:00:40 -0400, spir <denis.spir gmail.com> wrote:On 04/12/2011 11:51 PM, Steven Schveighoffer wrote:No, it doesn't enforce anything. The above compiles and runs. What it does is introduce subtle bugs. The way to fix it is to make the above an error.On Tue, 12 Apr 2011 17:21:57 -0400, spir <denis.spir gmail.com> wrote:Oh, that's what you meant! I find this a Good Thing, in that it enforces one bracing style (the right one, that does not eats one more line for just a '{').On 04/12/2011 09:21 PM, Steven Schveighoffer wrote:in Go, this: if(x) { gosWriteRoutineThatIDontKnowTheSyntaxOf("hello") } is equivalent to this in D: if(x) { } writeln("hello"); This is frankly unforgivable IMO. Of course it's fixable, but the attitude that "the coder should know better" doesn't really make me comfortable with it. And I hate the "brace on the same line" format (but this of course is not a real argument against it).int main(){ int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. (http://www.digitalmars.com/d/2.0/statement.html#DoStatement) [...] I think the grammar should be changed...yop!This is almost as bad as go's requirement for if statement opening block to be on the same line...why? I like Go's syntactuc diffs. (except for its "multi-for")About knowing or not about this (non/mis/-)feature, it's written down, and clearly, in all Go docs I've read. And one cannot miss it for very long anyway ;-)I know that if(xyz); is not *ever* what I meant, but in C it compiles. However, in D, it tells me I shouldn't do that. What results is less bugs because I can't make that mistake without the compiler complaining. I'm not saying that the spec isn't well defined, or the manual isn't clear, what I'm saying is, the attitude reflected in the rule is that greater burden is put on the developer to make sure they follow the rules without compiler enforcement. It makes me want to not use Go. And in fact, I will probably never use it as long as this rule is in place.Maybe, if not done already, a line starting with an opening brace should generate a parsing error.declaring temporary variables, not sure how it is in Go, but I'd assume something similar. -Steve
Apr 13 2011
On 13 April 2011 14:36, Steven Schveighoffer <schveiguy yahoo.com> wrote:On Tue, 12 Apr 2011 18:00:40 -0400, spir <denis.spir gmail.com> wrote: On 04/12/2011 11:51 PM, Steven Schveighoffer wrote:Does D throw an error at; if(expression && expression)*; *or only at if(expression); Because you could actually use the first one, alike this: <code> #include <stdio.h> bool test() { printf("test\n"); return false; } bool test2() { printf("test2\n"); return true; } int main() { if(test() && test2()); } </code> Output = "test" if test returns true, then: Output = "test" + "test2" Simply because its conditional, and if the first one fails, why bother evaluating the rest? -- // Yours sincerely // Emil 'Skeen' MadsenNo, it doesn't enforce anything. The above compiles and runs. What it does is introduce subtle bugs. The way to fix it is to make the above an error. About knowing or not about this (non/mis/-)feature, it's written down, andOn Tue, 12 Apr 2011 17:21:57 -0400, spir <denis.spir gmail.com> wrote: On 04/12/2011 09:21 PM, Steven Schveighoffer wrote:Oh, that's what you meant! I find this a Good Thing, in that it enforces one bracing style (the right one, that does not eats one more line for just a '{').int main(){in Go, this: if(x) { gosWriteRoutineThatIDontKnowTheSyntaxOf("hello") } is equivalent to this in D: if(x) { } writeln("hello"); This is frankly unforgivable IMO. Of course it's fixable, but the attitude that "the coder should know better" doesn't really make me comfortable with it. And I hate the "brace on the same line" format (but this of course is not a real argument against it).int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. ( http://www.digitalmars.com/d/2.0/statement.html#DoStatement) [...] I think the grammar should be changed...yop! This is almost as bad as go'srequirement for if statement opening block to be on the same line...why? I like Go's syntactuc diffs. (except for its "multi-for")clearly, in all Go docs I've read. And one cannot miss it for very long anyway ;-)I know that if(xyz); is not *ever* what I meant, but in C it compiles. However, in D, it tells me I shouldn't do that. What results is less bugs because I can't make that mistake without the compiler complaining. I'm not saying that the spec isn't well defined, or the manual isn't clear, what I'm saying is, the attitude reflected in the rule is that greater burden is put on the developer to make sure they follow the rules without compiler enforcement. It makes me want to not use Go. And in fact, I will probably never use it as long as this rule is in place. Maybe, if not done already, a line starting with an opening brace shouldgenerate a parsing error.declaring temporary variables, not sure how it is in Go, but I'd assume something similar. -Steve
Apr 13 2011
On Wed, 13 Apr 2011 09:44:54 -0400, Emil Madsen <sovende gmail.com> wrote:On 13 April 2011 14:36, Steven Schveighoffer <schveiguy yahoo.com> wrote:if(condition1 && condition2); is an error. However, an expression can be a statement: condition1 && condition2; Note, you can get around the limitation if that *really is* what you meant by doing: if(expression) {} An if statement is hard to justify for this, but I can see a while or for loop making sense here. -SteveI know that if(xyz); is not *ever* what I meant, but in C it compiles. However, in D, it tells me I shouldn't do that. What results is less bugs because I can't make that mistake without the compiler complaining.Does D throw an error at; if(expression && expression)*; *or only at if(expression); Because you could actually use the first one, alike this: <code> #include <stdio.h> bool test() { printf("test\n"); return false; } bool test2() { printf("test2\n"); return true; } int main() { if(test() && test2()); } </code> Output = "test" if test returns true, then: Output = "test" + "test2" Simply because its conditional, and if the first one fails, why bother evaluating the rest?
Apr 13 2011
On 04/13/2011 07:44 AM, Emil Madsen wrote:
On 13 April 2011 14:36, Steven Schveighoffer <schveiguy yahoo.com
<mailto:schveiguy yahoo.com>> wrote:
On Tue, 12 Apr 2011 18:00:40 -0400, spir <denis.spir gmail.com
<mailto:denis.spir gmail.com>> wrote:
On 04/12/2011 11:51 PM, Steven Schveighoffer wrote:
On Tue, 12 Apr 2011 17:21:57 -0400, spir
<denis.spir gmail.com <mailto:denis.spir gmail.com>> wrote:
On 04/12/2011 09:21 PM, Steven Schveighoffer wrote:
int main(){
int a,b;
do{
scanf("%d %d",&a,&b);
}while(a<b) //note missing semicolon here
return 0;
}
The grammar specifies this correctly, but then
again, the example uses the
semicolon.
(http://www.digitalmars.com/d/2.0/statement.html#DoStatement)
[...]
I think the grammar should be changed...
yop!
This is almost as bad as go's
requirement for if statement opening block to be on
the same line...
why? I like Go's syntactuc diffs. (except for its
"multi-for")
in Go, this:
if(x)
{
gosWriteRoutineThatIDontKnowTheSyntaxOf("hello")
}
is equivalent to this in D:
if(x)
{
}
writeln("hello");
This is frankly unforgivable IMO.
Of course it's fixable, but the attitude that "the coder
should know better"
doesn't really make me comfortable with it. And I hate the
"brace on the same
line" format (but this of course is not a real argument
against it).
Oh, that's what you meant! I find this a Good Thing, in that it
enforces one bracing style (the right one, that does not eats
one more line for just a '{').
No, it doesn't enforce anything. The above compiles and runs. What
it does is introduce subtle bugs.
The way to fix it is to make the above an error.
About knowing or not about this (non/mis/-)feature, it's written
down, and clearly, in all Go docs I've read. And one cannot miss
it for very long anyway ;-)
I know that if(xyz); is not *ever* what I meant, but in C it
compiles. However, in D, it tells me I shouldn't do that. What
results is less bugs because I can't make that mistake without the
compiler complaining.
I'm not saying that the spec isn't well defined, or the manual isn't
clear, what I'm saying is, the attitude reflected in the rule is
that greater burden is put on the developer to make sure they follow
the rules without compiler enforcement. It makes me want to not use
Go. And in fact, I will probably never use it as long as this rule
is in place.
Maybe, if not done already, a line starting with an opening
brace should generate a parsing error.
allows declaring temporary variables, not sure how it is in Go, but
I'd assume something similar.
-Steve
Does D throw an error at; if(expression && expression)*; *or only at
if(expression);
Because you could actually use the first one, alike this:
<code>
#include <stdio.h>
bool test()
{
printf("test\n");
return false;
}
bool test2()
{
printf("test2\n");
return true;
}
int main()
{
if(test() && test2());
}
</code>
Output = "test"
if test returns true, then: Output = "test" + "test2"
Simply because its conditional, and if the first one fails, why bother
evaluating the rest?
--
// Yours sincerely
// Emil 'Skeen' Madsen
I would argue that the more correct way to do this would be to separate
the statements that are used in the condition from the statements that
are not used in the condition.
if(test())
test2();
Since test2's return statement isn't used for anything means to me that
it doesn't belong in the conditional statement.
Apr 13 2011
On 13 April 2011 16:17, Kai Meyer <kai unixlords.com> wrote:On 04/13/2011 07:44 AM, Emil Madsen wrote:Well I agree that its more correct for the case posted, but it can just get somewhat messy, if your having a mix of conditionals say '&&' and '||'. Even tho its not really good style, some of the people I study with use this trick quite a lot converting functional programs, apparently (not my area of expertise). But surely I would go with your approach too, but if your having a deep nesting of conditionals, I guess that could give some heavily nested code too. (Atleast if you are to follow some specific coding standard). -- // Yours sincerely // Emil 'Skeen' MadsenOn 13 April 2011 14:36, Steven Schveighoffer <schveiguy yahoo.com <mailto:schveiguy yahoo.com>> wrote: On Tue, 12 Apr 2011 18:00:40 -0400, spir <denis.spir gmail.com <mailto:denis.spir gmail.com>> wrote: On 04/12/2011 11:51 PM, Steven Schveighoffer wrote: On Tue, 12 Apr 2011 17:21:57 -0400, spir <denis.spir gmail.com <mailto:denis.spir gmail.com>> wrote: On 04/12/2011 09:21 PM, Steven Schveighoffer wrote: int main(){ int a,b; do{ scanf("%d %d",&a,&b); }while(a<b) //note missing semicolon here return 0; } The grammar specifies this correctly, but then again, the example uses the semicolon. ( http://www.digitalmars.com/d/2.0/statement.html#DoStatement) [...] I think the grammar should be changed... yop! This is almost as bad as go's requirement for if statement opening block to be on the same line... why? I like Go's syntactuc diffs. (except for its "multi-for") in Go, this: if(x) { gosWriteRoutineThatIDontKnowTheSyntaxOf("hello") } is equivalent to this in D: if(x) { } writeln("hello"); This is frankly unforgivable IMO. Of course it's fixable, but the attitude that "the coder should know better" doesn't really make me comfortable with it. And I hate the "brace on the same line" format (but this of course is not a real argument against it). Oh, that's what you meant! I find this a Good Thing, in that it enforces one bracing style (the right one, that does not eats one more line for just a '{'). No, it doesn't enforce anything. The above compiles and runs. What it does is introduce subtle bugs. The way to fix it is to make the above an error. About knowing or not about this (non/mis/-)feature, it's written down, and clearly, in all Go docs I've read. And one cannot miss it for very long anyway ;-) I know that if(xyz); is not *ever* what I meant, but in C it compiles. However, in D, it tells me I shouldn't do that. What results is less bugs because I can't make that mistake without the compiler complaining. I'm not saying that the spec isn't well defined, or the manual isn't clear, what I'm saying is, the attitude reflected in the rule is that greater burden is put on the developer to make sure they follow the rules without compiler enforcement. It makes me want to not use Go. And in fact, I will probably never use it as long as this rule is in place. Maybe, if not done already, a line starting with an opening brace should generate a parsing error. allows declaring temporary variables, not sure how it is in Go, but I'd assume something similar. -Steve Does D throw an error at; if(expression && expression)*; *or only at if(expression); Because you could actually use the first one, alike this: <code> #include <stdio.h> bool test() { printf("test\n"); return false; } bool test2() { printf("test2\n"); return true; } int main() { if(test() && test2()); } </code> Output = "test" if test returns true, then: Output = "test" + "test2" Simply because its conditional, and if the first one fails, why bother evaluating the rest? -- // Yours sincerely // Emil 'Skeen' MadsenI would argue that the more correct way to do this would be to separate the statements that are used in the condition from the statements that are not used in the condition. if(test()) test2(); Since test2's return statement isn't used for anything means to me that it doesn't belong in the conditional statement.
Apr 13 2011
On 4/13/11, Steven Schveighoffer <schveiguy yahoo.com> wrote:I know that if(xyz); is not *ever* what I meant, but in C it compiles. However, in D, it tells me I shouldn't do that.I've been caught by DMD doing this a couple of times. It saved my butt. Thanks, Walter!
Apr 13 2011