for those of you purists that don't like break, continue and goto
-
That makes sense, especially given the type of algorithms you deal with in parsers and data structures. In the course of developing several large, complex applications, I've learned that having pieces of code that must stay in sync logically or follow the same algorithm is a failure point. Refactoring can help if i makes sense to move things into a method, and then have each location invoke the method. The hard part there can be figuring out a name for the thing: "
CheckToSeeIfMessageNeededAtThreadExit" is ugly :-D.Software Zen:
delete this;right. Extract Method is one of my favorite refactoring tools I don't use incredibly long names for private methods. I'll abbreviate something like the above to
_CheckMessageThread()Public members i usually go all out, and give it a really long name if it needs one.When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
A purist should be worried about touching control variables. Hmmm.
Jordan
-
ugh, VB. I use goto in some of my code. Perfectly acceptable place to use GOTO - generated state machine code:
public static bool AcceptsByte(Grimoire.ParseContext pc)
{
pc.EnsureStarted();
if (-1 == pc.Current) return false;
if ((48 == pc.Current))
{
pc.Advance();
goto AcceptsByte_s1;
}
if ((49 == pc.Current))
{
pc.Advance();
goto AcceptsByte_s2;
}
if ((50 == pc.Current))
{
pc.Advance();
goto AcceptsByte_s4;
}
if ((51 <= pc.Current && 57 >= pc.Current))
{
pc.Advance();
goto AcceptsByte_s3;
}
return false;
AcceptsByte_s1:
if (-1 == pc.Current) return true;
return -1 == pc.Advance();
AcceptsByte_s2:
if (-1 == pc.Current) return true;
if ((48 <= pc.Current && 57 >= pc.Current))
{
pc.Advance();
goto AcceptsByte_s3;
}
return -1 == pc.Advance();
AcceptsByte_s3:
if (-1 == pc.Current) return true;
if ((48 <= pc.Current && 57 >= pc.Current))
{
pc.Advance();
goto AcceptsByte_s1;
}
return -1 == pc.Advance();
AcceptsByte_s4:
if (-1 == pc.Current) return true;
if ((48 <= pc.Current && 52 >= pc.Current))
{
pc.Advance();
goto AcceptsByte_s3;
}
if ((53 == pc.Current))
{
pc.Advance();
goto AcceptsByte_s5;
}
if ((54 <= pc.Current && 57 >= pc.Current))
{
pc.Advance();
goto AcceptsByte_s1;
}
return -1 == pc.Advance();
AcceptsByte_s5:
if (-1 == pc.Current) return true;
if ((48 <= pc.Current && 52 >= pc.Current))
{
pc.Advance();
goto AcceptsByte_s1;
}
return -1 == pc.Advance();
}but then I wouldn't write that code by hand. Too error prone.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
Quote:
but then I wouldn't write that code by hand. Too error prone.
Isn't this exactly the point? All code gets compiled/interpreted/translated to jmps eventually. The goals of the written code should be correctness, understandability and simplicity. Leave the gotos and the clever techniques to the compiler.
-
throwwould be even more clear, definite and failure proof. (well I do see many kids using exactly that to 'not usegoto endlabel')Message Signature (Click to edit ->)
If finding the desired value is exceptional and unexpected and requiring special handling, then throwing an exception is appropriate. If it is the normal and desired case, exeactly what you expected: "Yeah, there it is!", then an exception is not the right mechanism.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
Quote:
but then I wouldn't write that code by hand. Too error prone.
Isn't this exactly the point? All code gets compiled/interpreted/translated to jmps eventually. The goals of the written code should be correctness, understandability and simplicity. Leave the gotos and the clever techniques to the compiler.
You trust your compiler?? Wow!
-
Quote:
but then I wouldn't write that code by hand. Too error prone.
Isn't this exactly the point? All code gets compiled/interpreted/translated to jmps eventually. The goals of the written code should be correctness, understandability and simplicity. Leave the gotos and the clever techniques to the compiler.
I'll optimize when i need to. that doesn't always make the code readable.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
I'll optimize when i need to. that doesn't always make the code readable.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
The reality is that with modern code, it's so far removed from the underlying machine language that gets executed that there's no point trying optimisations at the level of a break vs setting the iterator. Optimisations nowadays are at architectural levels - managing tight loops, using appropriate data structures, parallelisation, resource access.
-
The reality is that with modern code, it's so far removed from the underlying machine language that gets executed that there's no point trying optimisations at the level of a break vs setting the iterator. Optimisations nowadays are at architectural levels - managing tight loops, using appropriate data structures, parallelisation, resource access.
yes and no. it depends on whether you consider algorithmic optimizations to be architecture. For example, my first crack at LALR(1) table generation was taking 5 minutes to generate the tables for javascript. My second one cut that to a 5th of the time. The cost was code that was no longer "pure" and readable. It wasn't an architecture change. Unless you think it was. But I wouldn't agree, and I wrote it.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
Why not? What is the net value gain by the alternative you show?
-
Why not? What is the net value gain by the alternative you show?
there is none
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
Purist? Baaah! Think of this in terms of far-Eastern philosophy, to wit, Yin/Yang[^]. Always the spot of yin in the yang portion, the spot of yang in the yin portion. Neither can exist without the other. So, continue to use break as they help you goto a better place.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
-
Those two code snippets don't do the same thing. The first doesn't change arr, the second does.
How does it do that? If it does, it is a bug
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
Because neither one of these loops does anything except waste time. Was there perhaps a reason you wanted to find out if
valueToFindwas inarr? If there was, the first loop is almost right,ipoints to the matching entry on loop exit. Only problem is,igoes out of scope on loop exit. Sigh. The second loop always hasi== arr.Lengthon loop exit, andistill goes out of scope -
Because neither one of these loops does anything except waste time. Was there perhaps a reason you wanted to find out if
valueToFindwas inarr? If there was, the first loop is almost right,ipoints to the matching entry on loop exit. Only problem is,igoes out of scope on loop exit. Sigh. The second loop always hasi== arr.Lengthon loop exit, andistill goes out of scopethe code to do something is supposed to go in the loop body. i omitted it for the example. sorry i wasn't more clear.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
Purist? Baaah! Think of this in terms of far-Eastern philosophy, to wit, Yin/Yang[^]. Always the spot of yin in the yang portion, the spot of yang in the yin portion. Neither can exist without the other. So, continue to use break as they help you goto a better place.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
Prince Wang's programmer was coding software. His fingers danced upon the keyboard. The program compiled without and error message, and the program ran like a gentle wind. "Excellent!" the Prince exclaimed. "Your technique is faultless!" "Technique?" said the programmer, turning from his terminal, "What I follow is Tao -- beyond all techniques! When I first began to program, I would see before me the whole problem in one mass. After three years, I no longer saw this mass. Instead, I used subroutines. But now I see nothing. My whole being exists in a formless void. My senses are idle. My spirit, free to work without a plan, follows its own instinct. In short, my program writes itself. True, sometimes there are difficult problems. I see them coming, I slow down, I watch silently. Then I change a single line of code and the difficulties vanish like puffs of idle smoke. I then compile the program. I sit still and let the joy of the work fill my being. I close my eyes for a moment and then log off." Prince Wang said, "Would that all of my programmers were as wise!" - The Tao of Programming
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
-
why do this?
for(int i = 0;i
instead offor(int i = 0;i
hengh?? why you still use break?
:laugh:
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
only use Goto if you like spaghetti code ;)
-
only use Goto if you like spaghetti code ;)
i use gotos for generated state machine code so the code will look exactly like the graphs generated by graphviz. it makes the code more understandable. like this snippet, implementing q1 of the graph:
q1:
if((pc.Current>='0'&& pc.Current<='9')||
(pc.Current>='A'&& pc.Current<='Z')||
(pc.Current=='_')||
(pc.Current>='a'&& pc.Current<='z')) {
sb.Append((char)pc.Current);
pc.Advance();
goto q1;
}
return new System.Collections.Generic.KeyValuePair("id",sb.ToString());from (A Regular Expression Engine in C#[^]) there's supposed to be a picture at the link but it's no longer showing up for me. maybe it will for you. in any case, there's a time and a place for everything.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
