• Spacen Jasset (11/11) Mar 17 2014 I would like to subtract 60 days from a SysTime, but find that
• Vladimir Panteleev (5/8) Mar 17 2014 You can do this in a simpler way: t -= 60.days;
• Spacen Jasset (4/12) Mar 17 2014 Thanks. What devilish magic allows for the syntax 60.days? (how
• Adam D. Ruppe (7/9) Mar 17 2014 There's a function in core.time:
• Spacen Jasset (3/13) Mar 17 2014 Thanks Adam, is there a good explanation anywhere? It must be
• Ary Borenszweig (2/18) Mar 17 2014 http://dlang.org/function.html#pseudo-member
• Spacen Jasset (5/29) Mar 17 2014 Thanks but I still can't see how it fully explains this:
• Adam D. Ruppe (7/9) Mar 17 2014 There's a separate function days
• Spacen Jasset (2/11) Mar 17 2014 Thanks Adam, I see how the magic happens now.
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (4/5) Mar 17 2014 Here is another one:

"Spacen Jasset" <spacenjasset mailrazer.com> writes:

I would like to subtract 60 days from a SysTime, but find that 
SysTime.add!"days" is not available, unlike Systime.roll!"days" 
which is available.

main.d(18): Error: template instance add!("days") add!("days") 
does not match te
mplate declaration add(string units)(long value, AllowDayOverflow 
allowOverflow
= AllowDayOverflow.yes) if (units == "years" || units == "months")



Why is "days" add missing? How might I get round this?

Regards,

Spacen.

"Vladimir Panteleev" <vladimir thecybershadow.net> writes:

On Monday, 17 March 2014 at 11:11:26 UTC, Spacen Jasset wrote:
 I would like to subtract 60 days from a SysTime, but find that 
 SysTime.add!"days" is not available, unlike Systime.roll!"days" 
 which is available.

You can do this in a simpler way: t -= 60.days;

SysTime.add likely specializes on durations the length of which 
varies depending from their starting point, due to the varying 
number of days in a month or in a year.

"Spacen Jasset" <spacenjasset mailrazer.com> writes:

On Monday, 17 March 2014 at 11:52:08 UTC, Vladimir Panteleev 
wrote:
 On Monday, 17 March 2014 at 11:11:26 UTC, Spacen Jasset wrote:
 I would like to subtract 60 days from a SysTime, but find that 
 SysTime.add!"days" is not available, unlike 
 Systime.roll!"days" which is available.

 You can do this in a simpler way: t -= 60.days;

 SysTime.add likely specializes on durations the length of which 
 varies depending from their starting point, due to the varying 
 number of days in a month or in a year.

Thanks. What devilish magic allows for the syntax 60.days? (how 
does it work)

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Monday, 17 March 2014 at 14:31:54 UTC, Spacen Jasset wrote:
 Thanks. What devilish magic allows for the syntax 60.days? (how 
 does it work)

There's a function in core.time:

Duration days(int n);


D functions f(x, t...) can also be called x.f(t) (or x.f without 
parameters if there's no additional arguments).

This works on all types, it is called uniform function call 
syntax, or UFCS. It lets us extend other things with new methods.

"Spacen Jasset" <spacenjasset mailrazer.com> writes:

On Monday, 17 March 2014 at 14:39:16 UTC, Adam D. Ruppe wrote:
 On Monday, 17 March 2014 at 14:31:54 UTC, Spacen Jasset wrote:
 Thanks. What devilish magic allows for the syntax 60.days? 
 (how does it work)

 There's a function in core.time:

 Duration days(int n);


 D functions f(x, t...) can also be called x.f(t) (or x.f 
 without parameters if there's no additional arguments).

 This works on all types, it is called uniform function call 
 syntax, or UFCS. It lets us extend other things with new 
 methods.


Thanks Adam, is there a good explanation anywhere? It must be 
newish.

Ary Borenszweig <ary esperanto.org.ar> writes:

On 3/17/14, 12:11 PM, Spacen Jasset wrote:
 On Monday, 17 March 2014 at 14:39:16 UTC, Adam D. Ruppe wrote:
 On Monday, 17 March 2014 at 14:31:54 UTC, Spacen Jasset wrote:
 Thanks. What devilish magic allows for the syntax 60.days? (how does
 it work)

 There's a function in core.time:

 Duration days(int n);


 D functions f(x, t...) can also be called x.f(t) (or x.f without
 parameters if there's no additional arguments).

 This works on all types, it is called uniform function call syntax, or
 UFCS. It lets us extend other things with new methods.


 Thanks Adam, is there a good explanation anywhere? It must be newish.

http://dlang.org/function.html#pseudo-member

"Spacen Jasset" <spacenjasset mailrazer.com> writes:

On Monday, 17 March 2014 at 15:24:22 UTC, Ary Borenszweig wrote:
 On 3/17/14, 12:11 PM, Spacen Jasset wrote:
 On Monday, 17 March 2014 at 14:39:16 UTC, Adam D. Ruppe wrote:
 On Monday, 17 March 2014 at 14:31:54 UTC, Spacen Jasset wrote:
 Thanks. What devilish magic allows for the syntax 60.days? 
 (how does
 it work)

 There's a function in core.time:

 Duration days(int n);


 D functions f(x, t...) can also be called x.f(t) (or x.f 
 without
 parameters if there's no additional arguments).

 This works on all types, it is called uniform function call 
 syntax, or
 UFCS. It lets us extend other things with new methods.


 Thanks Adam, is there a good explanation anywhere? It must be 
 newish.

 http://dlang.org/function.html#pseudo-member

Thanks but I still can't see how it fully explains this: 
writeln("60 days: ", 60.days);

There is some type magic going on somewhere, because 60 is an int 
and days is a random method that happens to belong to Duration.

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Monday, 17 March 2014 at 16:16:20 UTC, Spacen Jasset wrote:
 int and days is a random method that happens to belong to 
 Duration.

There's a separate function days

https://github.com/D-Programming-Language/druntime/blob/master/src/core/time.d#L928

that one belongs to Duration

https://github.com/D-Programming-Language/druntime/blob/master/src/core/time.d#L1414

this one doesn't.


In the 60.days instance, it is calling the second function.

"Spacen Jasset" <spacenjasset mailrazer.com> writes:

On Monday, 17 March 2014 at 16:33:34 UTC, Adam D. Ruppe wrote:
 On Monday, 17 March 2014 at 16:16:20 UTC, Spacen Jasset wrote:
 int and days is a random method that happens to belong to 
 Duration.

 There's a separate function days

 https://github.com/D-Programming-Language/druntime/blob/master/src/core/time.d#L928

 that one belongs to Duration

 https://github.com/D-Programming-Language/druntime/blob/master/src/core/time.d#L1414

 this one doesn't.


 In the 60.days instance, it is calling the second function.

Thanks Adam, I see how the magic happens now.

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 03/17/2014 08:11 AM, Spacen Jasset wrote:

 Thanks Adam, is there a good explanation anywhere?

Here is another one:

   http://ddili.org/ders/d.en/ufcs.html

Ali