Re: Function template advice

[Jordan Wilson via Digitalmars-d-learn]

On Wednesday, 18 January 2017 at 22:39:02 UTC, Ali Çehreli wrote:

On 01/18/2017 02:02 PM, Jordan Wilson wrote:

[...]


Yes, can be better with something similar to the following:

struct Foo {
string bar;
}

string value(U : Foo)(U u) {
return u.bar;
}

string value(U : string)(U u) {
return u;
}

auto sameGroup(T,S) (T a, S b) {
static assert (is(T == string) || is(T == Foo));
static assert (is(S == string) || is(S == Foo));

import std.algorithm;
return equal (value(a), value(b));
}

void main() {
assert(sameGroup("a", "b") == false);
assert(sameGroup("a", Foo("a")) == true);
assert(sameGroup(Foo("x"), "b") == false);
assert(sameGroup(Foo("z"), Foo("z")) == true);
}

Ali


Nice, yes looks better thanks.
Jordan

Re: Function template advice

[Ali Çehreli via Digitalmars-d-learn]

On 01/18/2017 02:02 PM, Jordan Wilson wrote:

I have a simple comparison function:

struct Foo {
string bar;
}

auto sameGroup(T,S) (T a, S b) {
static assert (is(T == string) || is(T == Foo));
static assert (is(S == string) || is(S == Foo));

string aStr;
string bStr;
static if (is(T == string)){
aStr = a;
} else {
aStr = a.bar;
}
static if (is(S == string)){
bStr = b;
} else {
bStr = b.bar;
}
return equal (aStr,bStr);
}

This works, but just wondered if there was an easier way?

Is there a way to do "static if" in shorthand, like:
auto aStr = (static if (is(T==string)) ? a : a.bar


Yes, can be better with something similar to the following:

struct Foo {
string bar;
}

string value(U : Foo)(U u) {
return u.bar;
}

string value(U : string)(U u) {
return u;
}

auto sameGroup(T,S) (T a, S b) {
static assert (is(T == string) || is(T == Foo));
static assert (is(S == string) || is(S == Foo));

import std.algorithm;
return equal (value(a), value(b));
}

void main() {
assert(sameGroup("a", "b") == false);
assert(sameGroup("a", Foo("a")) == true);
assert(sameGroup(Foo("x"), "b") == false);
assert(sameGroup(Foo("z"), Foo("z")) == true);
}

Ali

Function template advice

[Jordan Wilson via Digitalmars-d-learn]

I have a simple comparison function:

struct Foo {
string bar;
}

auto sameGroup(T,S) (T a, S b) {
static assert (is(T == string) || is(T == Foo));
static assert (is(S == string) || is(S == Foo));

string aStr;
string bStr;
static if (is(T == string)){
aStr = a;
} else {
aStr = a.bar;
}
static if (is(S == string)){
bStr = b;
} else {
bStr = b.bar;
}
return equal (aStr,bStr);
}

This works, but just wondered if there was an easier way?

Is there a way to do "static if" in shorthand, like:
auto aStr = (static if (is(T==string)) ? a : a.bar