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version 2.108.0

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Template std.meta.ApplyLeft

Partially applies Template by binding its first (left) or last (right) arguments to args.

template ApplyLeft(alias Template, args...) ;

Behaves like the identity function when args is empty.

Contained Aliases

NameDescription
ApplyLeft

Parameters

NameDescription
Template template to partially apply
args arguments to bind

Returns

Template with arity smaller than or equal to Template

Example

// enum bool isImplicitlyConvertible(From, To)
import std.traits : isImplicitlyConvertible;

static assert(allSatisfy!(
    ApplyLeft!(isImplicitlyConvertible, ubyte),
    short, ushort, int, uint, long, ulong));

static assert(is(Filter!(ApplyRight!(isImplicitlyConvertible, short),
    ubyte, string, short, float, int) == AliasSeq!(ubyte, short)));

Example

import std.traits : hasMember, ifTestable;

struct T1
{
    bool foo;
}

struct T2
{
    struct Test
    {
        bool opCast(T : bool)() { return true; }
    }

    Test foo;
}

static assert(allSatisfy!(ApplyRight!(hasMember, "foo"), T1, T2));
static assert(allSatisfy!(ApplyRight!(ifTestable, a => a.foo), T1, T2));

Example

import std.traits : Largest;

alias Types = AliasSeq!(byte, short, int, long);

static assert(is(staticMap!(ApplyLeft!(Largest, short), Types) ==
            AliasSeq!(short, short, int, long)));
static assert(is(staticMap!(ApplyLeft!(Largest, int), Types) ==
            AliasSeq!(int, int, int, long)));

Example

import std.traits : FunctionAttribute, SetFunctionAttributes;

static void foo() @system;
static int bar(int) @system;

alias SafeFunctions = AliasSeq!(
    void function() @safe,
    int function(int) @safe);

static assert(is(staticMap!(ApplyRight!(
    SetFunctionAttributes, "D", FunctionAttribute.safe),
    typeof(&foo), typeof(&bar)) == SafeFunctions));

Authors

Walter Bright, David Nadlinger

License

Boost License 1.0.