Guess what I found in MFC's source code?
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You are not really trying to convince me that
error myroutine(){ HFILE hFile = NULL; error = success; if ((hFile = CreateFile(...))) { ReadFile(...); if (dwRead) { WriteFile(...); if (!dwWritten) { error = write; } } else { error = read; } CloseHandle(hFile); } else { error = create; } return error; }
is more readable and maintainable than:error myroutine(){ File f; if(!f.Create(...)) return create; if(!f.Read(...)) return read; if(!f.Write(...)) return write; return success; }Nenad Caklovic wrote:
error myroutine()
{
File f;
if(!f.Create(...))
return create;
if(!f.Read(...))
return read;
if(!f.Write(...))
return write;
return success;
}This kind is more elegant and neat to another style (a deep-nested conditioning), at least what I think. I always use this style in my code. Maxwell Chen
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toxcct wrote: have you ever heard or break keyword ? A break only breaks the loop belonged to that break. As:
int main()
{
int i, j, k;
printf("Begin:\n");
for(i = 0; i < 3; i++) {
for(j = 0; j < 3; j++) {
for(k = 0; k < 3; k++) {
if(k == 1)
break;
printf(" ~ k = %d.\n", k);
}
printf(" ~ j = %d,\n", j);
}
printf(" ~ i = %d,\n", i);
}
printf("End.\n");
return 0;
}Result:
Begin:
~ k = 0.
~ j = 0,
~ k = 0.
~ j = 1,
~ k = 0.
~ j = 2,
~ i = 0,
~ k = 0.
~ j = 0,
~ k = 0.
~ j = 1,
~ k = 0.
~ j = 2,
~ i = 1,
~ k = 0.
~ j = 0,
~ k = 0.
~ j = 1,
~ k = 0.
~ j = 2,
~ i = 2,
End.Maxwell Chen
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gotos are inherited from assembly code and that is the main reason it exist in C/C++. in all ways, i find MFC and other microsoft library codes awful to read. for example, they implement some of their functions into the header files instead of writing it into CPP files. moreover, they abuse of the imbricated operations...
TOXCCT >>> GEII power
toxcct wrote: MFC and other microsoft library codes awful to read. for example, they implement some of their functions into the header files instead of writing it into CPP files. The whole STL implementation is all written in header files. For ex, <vector> ... Maxwell Chen
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toxcct wrote: MFC and other microsoft library codes awful to read. for example, they implement some of their functions into the header files instead of writing it into CPP files. The whole STL implementation is all written in header files. For ex, <vector> ... Maxwell Chen
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we've powerful loop that perform clean jumps. we are not writing assembly here, so,
gotos must be avoided as much as possible. Don't forget a thing : your program must stay "DEBUGGABLE"
TOXCCT >>> GEII power
toxcct wrote: your program must stay "DEBUGGABLE" When talking about what non-debuggableness, it goes to exception-handling instead of goto jumps. In the old days when I was coding ADO stuff, for example:
bool Some_ADO_Type::FooBar(...)
{
// ...
// Everything is OK in the block.
return true;
} // Crashed here right after the (debug) yellow arrow passed this closing bracket.I traced deep into the hell bases... no idea why it threw such an exception, and no way to catch with VC++ 6. Finally, VC++ 7.x supports ISO C++, and there is such way:
bool FooBie()
try
{
return true;
}
catch(...)
{
return false;
}to catch such kind of god-d__n evil exceptions! Maxwell Chen
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toxcct wrote: your program must stay "DEBUGGABLE" When talking about what non-debuggableness, it goes to exception-handling instead of goto jumps. In the old days when I was coding ADO stuff, for example:
bool Some_ADO_Type::FooBar(...)
{
// ...
// Everything is OK in the block.
return true;
} // Crashed here right after the (debug) yellow arrow passed this closing bracket.I traced deep into the hell bases... no idea why it threw such an exception, and no way to catch with VC++ 6. Finally, VC++ 7.x supports ISO C++, and there is such way:
bool FooBie()
try
{
return true;
}
catch(...)
{
return false;
}to catch such kind of god-d__n evil exceptions! Maxwell Chen
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Maxwell Chen wrote: The whole STL implementation is all written in header files. yes, and it is what i reproach them. read the post i wrote just before yours here...
TOXCCT >>> GEII power
So you mean that there would be the header <vector> and the implementation, vector.cxx, in gcc or others!? Maxwell Chen
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i found this in "The C++ Language" from Bjarne Stroustrup, Chapter 13.7 : Organisation of the source code. (please appology mu english and my poor abilities in the translation (i've got the book, but in french). [...] In fact, the definition of out(), and all the declarations it depends on, are included into several compilation units. The compiler must generate the code (uniquely) when necessary, and optimize the reading multiple definitions process. In this strategy, the template functions are treatd exactly as inline functions. In this case, an obvious problem appears. Every element depending on the definition of out() is added into each file that use this function. Quantity of information that has to be treatd by the compiler is so considerably grown up. Another problem reside in the fact that users can become dependant on some declarations included uniquely for the out definition. This danger can be minimized while using namespaces, avoiding coding macros and reducing quantity of informations so included. The strategy of separate the compilation is the logical solution to this reasoning : if the template definition don't appear in the user code, none of its dependances can affect this code. This is why we split here the original out.c file into the following two :
// out.h
template<class T> void out (const T&);// out.c
#include <iostream>
#include "out.h"
export template<class T> void out (const T& t) { std::cerr << t; }the out.c file now contain all the requiered information to define out(), and out.h only contain useful information to call it. A user will only have to include the declaration (interface) :
#include "out.h"[...]. i let you notice that the definition and the implementation are well splited !!!
TOXCCT >>> GEII power
Here is what I found simply by Googling: http://www.comeaucomputing.com/techtalk/templates/#whylinkerror[^] A little snippet:
Why do I get a link error when compiling my templates?
Some compilers require that all function templates need to be made available in every translation
unit that it is used in. In effect, for those compilers, the bodies of template functions must be
made available in a header file. To repeat: that means those compilers won't allow them to be
defined in non-header files such as .cpp files. Furthermore, some compilers also require that
some functions be defined inline inside a class, and not outside of one.
Note that not all compilers require this. For instance, Comeau C++ does not in all cases (check
out http://www.comeaucomputing.com/4.0/docs/userman/ati.html for details on our current setup).
In short, Comeau C++ supports many models, including one which comes close to what the export
keyword's intentions are (as an extension).And on this point, note that the C++ export keyword is intended to alleviate the original
question. However, currently Comeau C++ is the only compiler known to support export. Therefore,
some compilers use such extensions referred to in the previous paragraph, or you need to put the
bodies of your functions in headers, if you are using a compiler which does not support export.So, the ability to put template implementations in the cpp file may be standard, I don't know, and you can't deduce it from reading "The C++ language", because Stroustrup is NOT responsible for that C++ standard, he is not Linus you know ;) But since very few compilers, and apparently none of the most used, are able to do it, you should just avoid trying. "After all it's just text at the end of the day. - Colin Davies "For example, when a VB programmer comes to my house, they may say 'does your pool need cleaning, sir ?' " - Christian Graus
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Every if is a goto, every for, while and do. The ?: operator is, function calls are, and returns are gotos to an adress that where picked up at a crowded plaza. try going without goto, and you will arrive nowhere. ;P
Flirt harder, I'm a Coder
mlog || Agile Programming | doxygen -
So you mean that there would be the header <vector> and the implementation, vector.cxx, in gcc or others!? Maxwell Chen
-
Here is what I found simply by Googling: http://www.comeaucomputing.com/techtalk/templates/#whylinkerror[^] A little snippet:
Why do I get a link error when compiling my templates?
Some compilers require that all function templates need to be made available in every translation
unit that it is used in. In effect, for those compilers, the bodies of template functions must be
made available in a header file. To repeat: that means those compilers won't allow them to be
defined in non-header files such as .cpp files. Furthermore, some compilers also require that
some functions be defined inline inside a class, and not outside of one.
Note that not all compilers require this. For instance, Comeau C++ does not in all cases (check
out http://www.comeaucomputing.com/4.0/docs/userman/ati.html for details on our current setup).
In short, Comeau C++ supports many models, including one which comes close to what the export
keyword's intentions are (as an extension).And on this point, note that the C++ export keyword is intended to alleviate the original
question. However, currently Comeau C++ is the only compiler known to support export. Therefore,
some compilers use such extensions referred to in the previous paragraph, or you need to put the
bodies of your functions in headers, if you are using a compiler which does not support export.So, the ability to put template implementations in the cpp file may be standard, I don't know, and you can't deduce it from reading "The C++ language", because Stroustrup is NOT responsible for that C++ standard, he is not Linus you know ;) But since very few compilers, and apparently none of the most used, are able to do it, you should just avoid trying. "After all it's just text at the end of the day. - Colin Davies "For example, when a VB programmer comes to my house, they may say 'does your pool need cleaning, sir ?' " - Christian Graus
jan larsen wrote: Stroustrup is NOT responsible for that C++ standard, he is not Linus you know ahahah. so you mean Linus Torvald is instead ? mouaahhhahah export is defined in the C++ standard, whatever you think, and it's sad to see those compilers not to implement it. :(
TOXCCT >>> GEII power
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jan larsen wrote: Stroustrup is NOT responsible for that C++ standard, he is not Linus you know ahahah. so you mean Linus Torvald is instead ? mouaahhhahah export is defined in the C++ standard, whatever you think, and it's sad to see those compilers not to implement it. :(
TOXCCT >>> GEII power
toxcct wrote: ahahah. so you mean Linus Torvald is instead ? mouaahhhahah No, what I meant was that unlike Linus, Bjarne has let go of his invention and given the full control to the implementors. toxcct wrote: export is defined in the C++ standard, whatever you think, and it's sad to see those compilers not to implement it. I agree, but since it doesn't help to moan about it, it's better to just accept that you probably have to wait a few more years before using that feature. "After all it's just text at the end of the day. - Colin Davies "For example, when a VB programmer comes to my house, they may say 'does your pool need cleaning, sir ?' " - Christian Graus
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NOOOOOO i'm not talking about that :( i say that if one day, you have to rewrite your code, or just maintain it, it would be much better if you could understand what you wrote back ?! isn't it ??? :confused:
TOXCCT >>> GEII power
Elegant way using goto is acceptable, just don't use goto in too queer way that nobody understands the code. As in the following program (ref: The Spigot Algorithm[^]), there's no goto used in it, but still hard to read the code, even though just some for loops:
long a=10000,b,c=2800,d,e,f[2801],g;
int main() {
for(;b-c ; ) f[++b]=a/5;
for(;d=0,g=c*2;c-=14,printf("%.4d",e+d/a),e=d%a)
for(b=c;d+=f[b]*a,f[b]=d%--g,d/=g--,--b;d*=b);
}Maxwell Chen
-
Here is what I found simply by Googling: http://www.comeaucomputing.com/techtalk/templates/#whylinkerror[^] A little snippet:
Why do I get a link error when compiling my templates?
Some compilers require that all function templates need to be made available in every translation
unit that it is used in. In effect, for those compilers, the bodies of template functions must be
made available in a header file. To repeat: that means those compilers won't allow them to be
defined in non-header files such as .cpp files. Furthermore, some compilers also require that
some functions be defined inline inside a class, and not outside of one.
Note that not all compilers require this. For instance, Comeau C++ does not in all cases (check
out http://www.comeaucomputing.com/4.0/docs/userman/ati.html for details on our current setup).
In short, Comeau C++ supports many models, including one which comes close to what the export
keyword's intentions are (as an extension).And on this point, note that the C++ export keyword is intended to alleviate the original
question. However, currently Comeau C++ is the only compiler known to support export. Therefore,
some compilers use such extensions referred to in the previous paragraph, or you need to put the
bodies of your functions in headers, if you are using a compiler which does not support export.So, the ability to put template implementations in the cpp file may be standard, I don't know, and you can't deduce it from reading "The C++ language", because Stroustrup is NOT responsible for that C++ standard, he is not Linus you know ;) But since very few compilers, and apparently none of the most used, are able to do it, you should just avoid trying. "After all it's just text at the end of the day. - Colin Davies "For example, when a VB programmer comes to my house, they may say 'does your pool need cleaning, sir ?' " - Christian Graus
I am not sure if I remembered correctly ... In some situation, a function template needs to be instantiated when across compilation units... If wrong, just forget it... ;P Maxwell Chen
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Elegant way using goto is acceptable, just don't use goto in too queer way that nobody understands the code. As in the following program (ref: The Spigot Algorithm[^]), there's no goto used in it, but still hard to read the code, even though just some for loops:
long a=10000,b,c=2800,d,e,f[2801],g;
int main() {
for(;b-c ; ) f[++b]=a/5;
for(;d=0,g=c*2;c-=14,printf("%.4d",e+d/a),e=d%a)
for(b=c;d+=f[b]*a,f[b]=d%--g,d/=g--,--b;d*=b);
}Maxwell Chen
-
Elegant way using goto is acceptable, just don't use goto in too queer way that nobody understands the code. As in the following program (ref: The Spigot Algorithm[^]), there's no goto used in it, but still hard to read the code, even though just some for loops:
long a=10000,b,c=2800,d,e,f[2801],g;
int main() {
for(;b-c ; ) f[++b]=a/5;
for(;d=0,g=c*2;c-=14,printf("%.4d",e+d/a),e=d%a)
for(b=c;d+=f[b]*a,f[b]=d%--g,d/=g--,--b;d*=b);
}Maxwell Chen
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Ha ha... ;P That is a famous algorithm that computes pi, with merely 150 characters in a small C program. :cool: Maxwell Chen
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Ha ha... ;P That is a famous algorithm that computes pi, with merely 150 characters in a small C program. :cool: Maxwell Chen
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toxcct wrote: and so powerful and useful mean beautiful for you ? No, I don't understand the code either! :doh: X| ;P Maxwell Chen
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From your bio: but in C/C++ (my favorites) since 1998. Hey, I started studying C++ since Nov 1998! :-D Maxwell Chen