digitalmars.D - std.boxed
- bobef (2/2) May 19 2005 So what is the use of these boxes? I can not undestand? Can someone help...
- Unknown W. Brackets (5/9) May 19 2005 Boxing is basically wannabe loose typing. It's for use when you want to...
- Andrew Fedoniouk (21/28) May 19 2005 Synonims:
- Ben Hinkle (6/29) May 19 2005 I agree Box is like discriminated unions in that they store data whose t...
- Andrew Fedoniouk (22/61) May 19 2005 :) Well, well, well, back to roots....
- bobef (6/35) May 20 2005 So why don't we just use void*-s? Their content is also know at run time...
- Unknown W. Brackets (14/19) May 20 2005 The idea is simply to have a class to put both a void* in and a
- bobef (2/21) May 20 2005
- Ben Hinkle (7/9) May 20 2005 A small clarification: an important feature is that integer types like i...
- Paul Bonser (9/62) May 24 2005 Dang, I'm gone for a while, and a neat feature like this gets added...
So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...
May 19 2005
"Unknown W. Brackets" <unknown simplemachines.org> Boxing is basically wannabe loose typing. It's for use when you want to pass something around without the baton holders having to know the type of it. It's like a void*, except with type information. Or, so I understand. -[Unknown]So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...
May 19 2005
So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...Synonims: VARIANT, discriminated union. Box is a structure which stores polymorphic data (not known at compile time) Typically implemented as struct box { byte type; // type of data in the box union { int intVal; double dblVal; void* ptrVal; } data; int getIntData() { if(type == INT) return data.intVal; .... } double getDblData() { .... } } Almost all scripting languages use kind of boxes as a representation of values. Andrew. "bobef" <bobef_member pathlink.com> wrote in message news:d6is5q$2gt9$1 digitaldaemon.com...So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...
May 19 2005
"Andrew Fedoniouk" <news terrainformatica.com> wrote in message news:d6jglj$2v9l$1 digitaldaemon.com...I agree Box is like discriminated unions in that they store data whose type is only known at run time but I wouldn't say it's a synonym since as you pointed out in a previous thread unions wrap a small number of known types and Boxes wrap all types. Maybe I'm nit-picking...So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...Synonims: VARIANT, discriminated union. Box is a structure which stores polymorphic data (not known at compile time) Typically implemented as struct box { byte type; // type of data in the box union { int intVal; double dblVal; void* ptrVal; } data; int getIntData() { if(type == INT) return data.intVal; .... } double getDblData() { .... } } Almost all scripting languages use kind of boxes as a representation of values. Andrew.
May 19 2005
I agree Box is like discriminated unions in that they store data whose type is only known at run time but I wouldn't say it's a synonym since as you pointed out in a previous thread unions wrap a small number of known types and Boxes wrap all types. Maybe I'm nit-picking...:) Well, well, well, back to roots.... ... let me to take my place on the rostrum... ok... (who the hell left this chalk here?) .... khm-khm.... Dear students! ... Discriminated union is such a type (especially an algebraic data type) might be described as a discriminated union if it is a sum type whose objects consist of a tag to say which part of the union they belong to and a value of the corresponding type. ... (Hooh, too long statement... not for use in MSDN...) To be serious: Andrew's Alexandrescu discriminated unions implementation based on type lists is just a particular case of them. The Box is another implementation of DU limited by type system of D language. :-P Andrew. "Ben Hinkle" <ben.hinkle gmail.com> wrote in message news:d6jiik$306n$1 digitaldaemon.com..."Andrew Fedoniouk" <news terrainformatica.com> wrote in message news:d6jglj$2v9l$1 digitaldaemon.com...I agree Box is like discriminated unions in that they store data whose type is only known at run time but I wouldn't say it's a synonym since as you pointed out in a previous thread unions wrap a small number of known types and Boxes wrap all types. Maybe I'm nit-picking...So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...Synonims: VARIANT, discriminated union. Box is a structure which stores polymorphic data (not known at compile time) Typically implemented as struct box { byte type; // type of data in the box union { int intVal; double dblVal; void* ptrVal; } data; int getIntData() { if(type == INT) return data.intVal; .... } double getDblData() { .... } } Almost all scripting languages use kind of boxes as a representation of values. Andrew.
May 19 2005
So why don't we just use void*-s? Their content is also know at run time. I mean we know what we put in there so we know what we expect to put out. Or at least most of the cases. Anyway I think I understand it better now but I still can't think of any use.. I don't say it is useless I just can't think of one in this moment... In article <d6jglj$2v9l$1 digitaldaemon.com>, Andrew Fedoniouk says...So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...Synonims: VARIANT, discriminated union. Box is a structure which stores polymorphic data (not known at compile time) Typically implemented as struct box { byte type; // type of data in the box union { int intVal; double dblVal; void* ptrVal; } data; int getIntData() { if(type == INT) return data.intVal; .... } double getDblData() { .... } } Almost all scripting languages use kind of boxes as a representation of values. Andrew. "bobef" <bobef_member pathlink.com> wrote in message news:d6is5q$2gt9$1 digitaldaemon.com...So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...
May 20 2005
The idea is simply to have a class to put both a void* in and a
TypeInfo, essentially.
The use might be for something like this:
Box coolfunction(int mode)
{
if (mode == 1)
return box(5);
elseif (mode == 2)
return box("testing");
else
return box(false);
}
Or similar. For class members too.
-[Unknown]
So why don't we just use void*-s? Their content is also know at run time. I
mean
we know what we put in there so we know what we expect to put out. Or at least
most of the cases. Anyway I think I understand it better now but I still can't
think of any use.. I don't say it is useless I just can't think of one in this
moment...
May 20 2005
Thanks. I understand now. It is cool. I like it.
In article <d6k5fl$fda$1 digitaldaemon.com>, Unknown W. Brackets says...
The idea is simply to have a class to put both a void* in and a
TypeInfo, essentially.
The use might be for something like this:
Box coolfunction(int mode)
{
if (mode == 1)
return box(5);
elseif (mode == 2)
return box("testing");
else
return box(false);
}
Or similar. For class members too.
-[Unknown]
So why don't we just use void*-s? Their content is also know at run time. I
mean
we know what we put in there so we know what we expect to put out. Or at least
most of the cases. Anyway I think I understand it better now but I still can't
think of any use.. I don't say it is useless I just can't think of one in this
moment...
May 20 2005
"Unknown W. Brackets" <unknown simplemachines.org> wrote in message news:d6k5fl$fda$1 digitaldaemon.com...The idea is simply to have a class to put both a void* in and a TypeInfo, essentially.A small clarification: an important feature is that integer types like ints, longs and doubles and array-references (ptr + length) are stored "inline" meaning what is stored is not a void* pointing to an int but the actual int is stored. So it is very efficient to pass around boxes of small types like ints.
May 20 2005
bobef wrote:So why don't we just use void*-s? Their content is also know at run time. I mean we know what we put in there so we know what we expect to put out. Or at least most of the cases. Anyway I think I understand it better now but I still can't think of any use.. I don't say it is useless I just can't think of one in this moment... In article <d6jglj$2v9l$1 digitaldaemon.com>, Andrew Fedoniouk says...Dang, I'm gone for a while, and a neat feature like this gets added... This'll be great for implementing a scripting language in my game engine.. :) -- -PIB -- "C++ also supports the notion of *friends*: cooperative classes that are permitted to see each other's private parts." - Grady BoochSo what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...Synonims: VARIANT, discriminated union. Box is a structure which stores polymorphic data (not known at compile time) Typically implemented as struct box { byte type; // type of data in the box union { int intVal; double dblVal; void* ptrVal; } data; int getIntData() { if(type == INT) return data.intVal; .... } double getDblData() { .... } } Almost all scripting languages use kind of boxes as a representation of values. Andrew. "bobef" <bobef_member pathlink.com> wrote in message news:d6is5q$2gt9$1 digitaldaemon.com...So what is the use of these boxes? I can not undestand? Can someone help me... maybe a little example and explanation why it is needed? Thank you...
May 24 2005