• pineapple (3/3) Aug 26 2016 I've grown to very much appreciate how context initialization and
• Cauterite (4/7) Aug 26 2016 Yep, scope guards.
• pineapple (27/34) Aug 26 2016 What I had in mind was something more like this, but not quite so
• pineapple (4/4) Aug 26 2016 I would just love if I could express this as something more like
• Adam D. Ruppe (13/16) Aug 26 2016 You don't need to do anything special for that in D, structs are
• Daniel Kozak via Digitalmars-d-learn (8/12) Aug 27 2016 void main(string[] args)

pineapple <meapineapple gmail.com> writes:

I've grown to very much appreciate how context initialization and 
teardown can be very conveniently handled using `with` in Python. 
Is there any clean way to imitate this syntax in D?

Cauterite <cauterite gmail.com> writes:

On Friday, 26 August 2016 at 23:28:27 UTC, pineapple wrote:
 I've grown to very much appreciate how context initialization 
 and teardown can be very conveniently handled using `with` in 
 Python. Is there any clean way to imitate this syntax in D?

Yep, scope guards.

auto p = OpenProcess(...);
scope(exit) {CloseHandle(p);};

pineapple <meapineapple gmail.com> writes:

On Friday, 26 August 2016 at 23:30:15 UTC, Cauterite wrote:
 On Friday, 26 August 2016 at 23:28:27 UTC, pineapple wrote:
 I've grown to very much appreciate how context initialization 
 and teardown can be very conveniently handled using `with` in 
 Python. Is there any clean way to imitate this syntax in D?

 Yep, scope guards.

 auto p = OpenProcess(...);
 scope(exit) {CloseHandle(p);};

What I had in mind was something more like this, but not quite so 
messy-looking. Though after having actually written it out I'm 
wondering if it's not better to just keep it looking like this, 
or similar, rather than make it part of the language. It's not 
_too_ hideous.

     import std.stdio;

     void context(Context, Dg)(Context context, Dg content){
         scope(exit) context.conclude;
         content(context);
     }

     struct File{
         this(string path){
             writeln("open a file");
         }
         void write(){
             writeln("write some data");
         }
         void conclude(){
             writeln("close the file");
         }
     }

     void main(){
         context(File("some_file.txt"), (File file){
             file.write();
         });
     }

pineapple <meapineapple gmail.com> writes:

I would just love if I could express this as something more like


     context(auto file = File("some_file.txt")){
         file.write();
     }

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

On Saturday, 27 August 2016 at 00:04:47 UTC, pineapple wrote:
     context(auto file = File("some_file.txt")){
         file.write();
     }

You don't need to do anything special for that in D, structs are 
destructed automatically. Plain

auto file = File("some_file.txt");
file.write();


will automatically close file when it goes out of scope. If you 
want it to go out of scope earlier, you can:

{
auto file = File("some_file.txt");
file.write();
}

the curly braces around it will make a new scope, so the 
destructor, which closes the file, will be called at the }.

Daniel Kozak via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:

Dne 27.8.2016 v 02:04 pineapple via Digitalmars-d-learn napsal(a):

 I would just love if I could express this as something more like


     context(auto file = File("some_file.txt")){
         file.write();
     }

void main(string[] args)
{
     with(File("some_file.txt"))
     {
         write();
     }
}