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digitalmars.D.learn - importing std.algorithm breaks std.string.count

reply Seth Hoenig <seth.a.hoenig gmail.com> writes:
I have these two minimal programs:


import std.string;
void main()
{
    string str = "abc";
    int i = str.count("ab");

}



and:



import std.string;
import std.algorithm;
void main()
{
    string str = "abc";
    int i = str.count("ab");

}



The only difference is line 2, where I import std.algorithm.
The first program compiles fine, but the second program does not compile,
spitting out the error message:

bash-3.2$ dmd -ofdummy dummy.d
/u/sah2659/dmd2/linux/bin/../../src/phobos/std/functional.d(176): Error:
static assert  "Bad binary function q{a == b}. You need to use a valid D
expression using symbols a of type dchar and b of type string."
/u/sah2659/dmd2/linux/bin/../../src/phobos/std/functional.d(179):
instantiated from here: Body!(dchar,string)
/u/sah2659/dmd2/linux/bin/../../src/phobos/std/algorithm.d(3410):
instantiated from here: result!(dchar,string)
dummy.d(7):        instantiated from here: count!("a == b",string,string)


I can't imagine I'm the first person to notice a bug like this, so is there
something I am doing wrong?
Sep 17 2010
parent reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Fri, 17 Sep 2010 17:15:31 -0400, Seth Hoenig <seth.a.hoenig gmail.com>  
wrote:

 I have these two minimal programs:


 import std.string;
 void main()
 {
     string str = "abc";
     int i = str.count("ab");

 }



 and:



 import std.string;
 import std.algorithm;
 void main()
 {
     string str = "abc";
     int i = str.count("ab");

 }



 The only difference is line 2, where I import std.algorithm.
 The first program compiles fine, but the second program does not compile,
 spitting out the error message:

 bash-3.2$ dmd -ofdummy dummy.d
 /u/sah2659/dmd2/linux/bin/../../src/phobos/std/functional.d(176): Error:
 static assert  "Bad binary function q{a == b}. You need to use a valid D
 expression using symbols a of type dchar and b of type string."
 /u/sah2659/dmd2/linux/bin/../../src/phobos/std/functional.d(179):
 instantiated from here: Body!(dchar,string)
 /u/sah2659/dmd2/linux/bin/../../src/phobos/std/algorithm.d(3410):
 instantiated from here: result!(dchar,string)
 dummy.d(7):        instantiated from here: count!("a == b",string,string)


 I can't imagine I'm the first person to notice a bug like this, so is  
 there
 something I am doing wrong?
I see two bugs here. First, this should be an ambiguity error, because count matches both std.algorithm.count and std.string.count. The compiler should refuse to compile this I think. Second, std.algorithm.count looks like this: size_t count(alias pred = "a == b", Range, E)(Range r, E value) if (isInputRange!(Range)) So, E can be any type, completely unrelated to strings, I could do: count!(string, int[]) which makes no sense. I think the sig should be size_t count(alias pred = "a == b", Range, E)(Range r, E value) if (isInputRange!(Range) && isImplicitlyConvertable!(E, ElementType!(Range))) -Steve
Sep 17 2010
next sibling parent Seth Hoenig <seth.a.hoenig gmail.com> writes:
Submitted *Issue 4883 <http://d.puremagic.com/issues/show_bug.cgi?id=4883>


*
On Fri, Sep 17, 2010 at 4:30 PM, Steven Schveighoffer
<schveiguy yahoo.com>wrote:

 On Fri, 17 Sep 2010 17:15:31 -0400, Seth Hoenig <seth.a.hoenig gmail.com>
 wrote:

  I have these two minimal programs:
 import std.string;
 void main()
 {
    string str = "abc";
    int i = str.count("ab");

 }



 and:



 import std.string;
 import std.algorithm;
 void main()
 {
    string str = "abc";
    int i = str.count("ab");

 }



 The only difference is line 2, where I import std.algorithm.
 The first program compiles fine, but the second program does not compile,
 spitting out the error message:

 bash-3.2$ dmd -ofdummy dummy.d
 /u/sah2659/dmd2/linux/bin/../../src/phobos/std/functional.d(176): Error:
 static assert  "Bad binary function q{a == b}. You need to use a valid D
 expression using symbols a of type dchar and b of type string."
 /u/sah2659/dmd2/linux/bin/../../src/phobos/std/functional.d(179):
 instantiated from here: Body!(dchar,string)
 /u/sah2659/dmd2/linux/bin/../../src/phobos/std/algorithm.d(3410):
 instantiated from here: result!(dchar,string)
 dummy.d(7):        instantiated from here: count!("a == b",string,string)


 I can't imagine I'm the first person to notice a bug like this, so is
 there
 something I am doing wrong?
I see two bugs here. First, this should be an ambiguity error, because count matches both std.algorithm.count and std.string.count. The compiler should refuse to compile this I think. Second, std.algorithm.count looks like this: size_t count(alias pred = "a == b", Range, E)(Range r, E value) if (isInputRange!(Range)) So, E can be any type, completely unrelated to strings, I could do: count!(string, int[]) which makes no sense. I think the sig should be size_t count(alias pred = "a == b", Range, E)(Range r, E value) if (isInputRange!(Range) && isImplicitlyConvertable!(E, ElementType!(Range))) -Steve
Sep 17 2010
prev sibling parent reply "Daniel Murphy" <yebblies nospamgmail.com> writes:
"Steven Schveighoffer" <schveiguy yahoo.com> wrote in message 
news:op.vi64pdhveav7ka localhost.localdomain...
 Second, std.algorithm.count looks like this:

 size_t count(alias pred = "a == b", Range, E)(Range r, E value) if 
 (isInputRange!(Range))

 So, E can be any type, completely unrelated to strings, I could do:

 count!(string, int[]) which makes no sense.

 I think the sig should be

 size_t count(alias pred = "a == b", Range, E)(Range r, E value) if 
 (isInputRange!(Range) && isImplicitlyConvertable!(E, ElementType!(Range)))

 -Steve
Except you can call it like this: string s = "1234"; int[] a = [1, 2, 3]; count!"cast(int)(a - '0') == b.length"(s, a); Which is perfectly valid.
Sep 22 2010
parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Thu, 23 Sep 2010 02:19:55 -0400, Daniel Murphy  
<yebblies nospamgmail.com> wrote:

 "Steven Schveighoffer" <schveiguy yahoo.com> wrote in message
 news:op.vi64pdhveav7ka localhost.localdomain...
 Second, std.algorithm.count looks like this:

 size_t count(alias pred = "a == b", Range, E)(Range r, E value) if
 (isInputRange!(Range))

 So, E can be any type, completely unrelated to strings, I could do:

 count!(string, int[]) which makes no sense.

 I think the sig should be

 size_t count(alias pred = "a == b", Range, E)(Range r, E value) if
 (isInputRange!(Range) && isImplicitlyConvertable!(E,  
 ElementType!(Range)))

 -Steve
Except you can call it like this: string s = "1234"; int[] a = [1, 2, 3]; count!"cast(int)(a - '0') == b.length"(s, a); Which is perfectly valid.
and insane :) count(s, cast(char)(a.length + '0')); -Steve
Sep 23 2010