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digitalmars.D.learn - Re: A tutorial on D templates

reply "DNewbie" <run3 myopera.com> writes:
I can't understand it. Why would someone need template programming. What
problem does template solve?
-- 
  
  D
Jan 13 2012
next sibling parent reply Peter Alexander <peter.alexander.au gmail.com> writes:
On 13/01/12 10:48 PM, DNewbie wrote:

 I can't understand it. Why would someone need template programming. What
problem does template solve?



Suppose you want to write a function to get the minimum of two integers. 
It's easy:

int min(int a, int b)
{
     return a < b ? a : b;
}

Suppose then you want to use it with floats. You now need to write 
another function.

float min(float a, float b)
{
     return a < b ? a : b;
}

Suppose you then want to use it with doubles, reals, complex numbers, 
strings etc. etc.  You would quickly get tired of writing these 
functions, and more importantly you would likely make mistakes at some 
point.

Templates allow you to solve this problem by writing the function once 
with placeholders for types:

T min(T)(T a, T b)
{
     return a < b ? a : b;
}

This will work for ints, floats, doubles... Anything that has a < 
operator will work.

There's much more you can do with templates, but that's the fundamental 
problem that they solve.
Jan 13 2012
parent Philippe Sigaud <philippe.sigaud gmail.com> writes:
 On 13/01/12 10:48 PM, DNewbie wrote:

 I can't understand it. Why would someone need template programming. What
problem does template solve?









Well read on and see :-)

Peter:

 Suppose you want to write a function to get the minimum of two integers.
 It's easy:



 Oh.. I see.
 Thank you everybody.



And that's the first, more visible part of templates, a bit like
generics in Java.
Template are incomplete pieces of code with left-empty 'slots' which
you can fill at compile-time to decide what code will be compiled.
You can generate entire functions / class hierarchies or nicely
crafted-for-your-need code / pre-computed-by-the-compiler code with
templates.

Philippe
Jan 14 2012
prev sibling next sibling parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 01/13/2012 02:48 PM, DNewbie wrote:

 I can't understand it. Why would someone need template programming. What
problem does template solve?



Here is another resource that tries to answer that question:

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

"Parts of the source code may be left to the compiler to be filled in 
until that part is actually used in the program."

Ali
Jan 13 2012
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 01/14/2012 12:11 AM, Philippe Sigaud wrote:

 On Sat, Jan 14, 2012 at 01:08, Ali Çehreli<acehreli yahoo.com>  wrote:




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







 Hi Ali, I discovered you had a chapter on templates just a few days
 ago.



That chapter is intentionally incomplete. I think function, struct, and 
class templates and their uses with type template parameters are the 
most common. (That's a C++ programmer talking. ;)) I've left the rest of 
templates to a later chapter.


 I'll go and read it.



Thank you. Please ignore the Inglish ;) mistakes for now. It is 
constantly being corrected by my editor (Ergin Güney) and I.


 I think I'll add a ressources/further
 reading part in my doc and put a link to your chapter.



Thank you. I will do the same. It will be easier if it gets a permanent 
home, in addition to its github page ( 
https://github.com/PhilippeSigaud/D-templates-tutorial ).


 Philippe



Ali
Jan 14 2012
parent =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 01/14/2012 07:49 AM, Philippe Sigaud wrote:


 That's cool, because the D community is small enough and still
 dispersed enough that we should link one another to bring it all
 together.



Thank you very much for your link! :)

And I've finally found time to create two links to your 'D Templates: A 
Tutorial' from the following page

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

Ali

P.S. Going off-topic, the following chapters of 'Programming in D' have 
been translated since the last announcement:

* Redirecting Standard Input and Output Streams
* Files
* auto and typeof
* Name Space
* The for Loop
* The Ternary Operator ?:
* Literals
* Formatted Output

Now the book can also be downloaded as pdf from the [Download as PDF] 
link on chapter headers:

   http://ddili.org/ders/d.en/index.html
Jan 31 2012
prev sibling next sibling parent Philippe Sigaud <philippe.sigaud gmail.com> writes:
On Sat, Jan 14, 2012 at 01:08, Ali =C3=87ehreli <acehreli yahoo.com> wrote:


 Here is another resource that tries to answer that question:

 =C2=A0http://ddili.org/ders/d.en/templates.html

 "Parts of the source code may be left to the compiler to be filled in unt=




 that part is actually used in the program."



Hi Ali, I discovered you had a chapter on templates just a few days
ago. I'll go and read it. I think I'll add a ressources/further
reading part in my doc and put a link to your chapter.

Philippe
Jan 14 2012
prev sibling next sibling parent Philippe Sigaud <philippe.sigaud gmail.com> writes:
On Sat, Jan 14, 2012 at 15:56, Ali =C3=87ehreli <acehreli yahoo.com> wrote:

 On 01/14/2012 12:11 AM, Philippe Sigaud wrote:

 On Sat, Jan 14, 2012 at 01:08, Ali =C3=87ehreli<acehreli yahoo.com> =C2=







 =C2=A0 http://ddili.org/ders/d.en/templates.html








 Hi Ali, I discovered you had a chapter on templates just a few days
 ago.



 That chapter is intentionally incomplete. I think function, struct, and
 class templates and their uses with type template parameters are the most
 common. (That's a C++ programmer talking. ;)) I've left the rest of
 templates to a later chapter.



I agree. Your goal is not exactly the same as mine: you intend to give
a view on the entire language, for beginners, whereas I intend my doc
to be a deep plunge into templates, as complete as possible.


 I'll go and read it.



 Thank you. Please ignore the Inglish ;) mistakes for now. It is constantl=




 being corrected by my editor (Ergin G=C3=BCney) and I.



What I see is quite readable :-)



 I think I'll add a ressources/further
 reading part in my doc and put a link to your chapter.



 Thank you. I will do the same.



That's cool, because the D community is small enough and still
dispersed enough that we should link one another to bring it all
together.


 It will be easier if it gets a permanent
 home, in addition to its github page (
 https://github.com/PhilippeSigaud/D-templates-tutorial ).



I have no permanent home for my D projects, nor do I intend to do. You
can link to the Github project, that's what people do. Or directly to
the pdf, if you wish.
Jan 14 2012
prev sibling parent Philippe Sigaud <philippe.sigaud gmail.com> writes:
On Tue, Jan 31, 2012 at 09:12, Ali =C3=87ehreli <acehreli yahoo.com> wrote:

 On 01/14/2012 07:49 AM, Philippe Sigaud wrote:


 That's cool, because the D community is small enough and still
 dispersed enough that we should link one another to bring it all
 together.



 Thank you very much for your link! :)



That's quite normal.


 And I've finally found time to create two links to your 'D Templates: A
 Tutorial' from the following page

 =C2=A0http://ddili.org/ders/d.en/templates.html



And thank you too!


 Ali

 P.S. Going off-topic, the following chapters of 'Programming in D' have b=




 translated since the last announcement:

 * Redirecting Standard Input and Output Streams
 * Files
 * auto and typeof
 * Name Space
 * The for Loop
 * The Ternary Operator ?:
 * Literals
 * Formatted Output

 Now the book can also be downloaded as pdf from the [Download as PDF] lin=




 on chapter headers:

 =C2=A0http://ddili.org/ders/d.en/index.html



I think you should make an independent announce on D.announce and
D.learn. And maybe then monthly (or every three month, say) updates on
the state of your book.
Jan 31 2012