Code Neatness

[Michael Haines]

I am already using two monitors, so I am talking about REALLY long lines! :-D

[Frank W Wu]

The good practice is “Lazy Evaluation” – declaring as late as possible, and keep it within the scope only (hide it from outside). If you declare everything in the beginning of a function, you probably will forget to clean up the residual data before using it.

[Mike Dimmick]

Ravi Bhavnani wrote:

can't imagine I'd use one that didn't do that as part of standard optimization! Code hoisting has been around for decades and is pretty mature technology.

If the object has a constructor or destructor, the C++ standard requires that it is destroyed and a new object created on every iteration of the loop. But the compiler will construct the object in the same space each time.

DoEvents: Generating unexpected recursion since 1991

[z974647]

Here's a free site for cleaning up your SQL...just paste your code in it and hit the Prettify! button.... www.simple-talk.com/prettifier/

[Mike Dimmick]

Larry Osterman and others have documented that Hungarian Notation originated with Charles Simonyi in the apps group at Microsoft. It was the systems group that bastardized it to the form we see in Windows where the syntactic type, which can be checked by the compiler, is encoded in the name. (Someone from the systems group, who was blamed by Larry for the error, here[^] claims that it was the people who authored the documentation that screwed it up!) I think true Hungarian would have called your variables iOuter and iInner, where the i prefix indicates an index into an array, but of course the problem is that i has been overloaded in "Systems Hungarian" (or "Anti-Hungarian" as Rick Schaut calls it[^]) to mean 'int'.

DoEvents: Generating unexpected recursion since 1991

[Mike Dimmick]

Funnily enough I was looking at JIT output last night! How do I see what the JIT compiled, anyway?[^]

DoEvents: Generating unexpected recursion since 1991

[Lowell Boggs]

Declaring variables at the top of a function or program is bad idea. Consider the following:

void function()
{
int i;

  // use 'i' for purpose 1
  ...
  // use 'i' for purpose 2
  ...
  // use 'i' for purpose 3
  ...

  if(i == 14)
  {
    // crash the program
  }

}

At the bottom of the function, 'i' is the accidental work product of the last place that it was used. Suppose this function is 200 lines long? Is the user supposed to hand examine every single place a variable is modified in order to understand what its value is currently being used for? Instead, declare variables as close to the point that they are actually used and make sure that they go out of scope as quickly after that as possible to reduce confusion to later maintainers. Confusion is the root of all evil in s/w. Lowell used.

[El Corazon]

mhaines@1amadeus.com wrote:

I am already using two monitors, so I am talking about REALLY long lines!

so use two 30" monitors.... come on, use it as an excuse... you know you want them!

_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

[El Corazon]

Ri Qen-Sin wrote:

I'm trying to seek agreement… so was I right when I said so?

yes, and no. If your code loops or branches, it matters where you declare your variables. For instance declaring all your variables up front pulls a lot of space off the stack or heap, creates overhead, and if you branch or exit early, you have created unnecessary overhead. If your code branches with an if or a switch, you never want to incur the overhead associated with unused branches. on the other side, declaring a variable inside of a loop means that this variable will be allocated and deallocated often. By moving the declaration outside of the loop, your cost is significantly less performance wise. BUT! The rule above still applies. You do not have to move it to the front of the function, though you can if you don't branch or exit early.

_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

[El Corazon]

Steve Echols wrote:

but if you try that in C++ you get a duplicate definition error on i.

That was just MS. Other compilers don't have that problem, though as mentioned MS can fix it with an option.

_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

[El Corazon]

Shog9 wrote:

Good grief. Do people not know how to generate assembler output from their compilers anymore?

No, most do not.... :sigh: :sigh:

_________________________ Asu no koto o ieba, tenjo de nezumi ga warau. Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

[Ravi Bhavnani]

Code hoisting applies to code that can be hoisted. :) /ravi

My new year resolution: 2048 x 1536 Home | Music | Articles | Freeware ravib(at)ravib(dot)com

[W Balboos GHB]

Odd comment - I've found that for managed code (somewhat common these days), if I declare outside the loop and load the values into a containers (e.g., ArrayList), they all have the same value when I'm done. Now, If I declare inside the loop, each is a newly created version and it works as expected. Roughly speaking: This will work as expected ArrayList ^tmp = gcnew ArrayList(); for(int i=0;iLength; ++i) { Object ^x = ContainerFullOfObjPtrs[i]; tmp->Add(x); } This is usually somewhat disappointing ArrayList ^tmp = gcnew ArrayList(); Object ^x = gcnew Object(); for(int i=0; i; Length; ++i) { x = ContainerFullOfObjPtrs[i]; tmp->Add(x); } "The difference between genius and stupidity is that genius has its limits." - Albert Einstein "How do you find out if you're unwanted if everyone you try to ask tells you to go away?" - Balboos HaGadol

[David Crow]

Since it was your opinion, it was neither right nor wrong.

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

[chaiguy1337]

As I recall, the way I learned Hungarian notation was developing for the mac in C++, we would use "m" to denote a member variable (eg. mUrl), and maybe "p" for a parameter, etc. Typesafe languages don't need the type as a prefix, but often there is some conflict between what kind of a variable you're using.

“Time and space can be a bitch.” –Gushie, Quantum Leap {o,o}.oO( Want a great RSS reader? Try FeedBeast! ) |)””’) -”-”-

[Timothy W Okrey]

I have been programming since 83. I have worked with a whole slew of languages and OS's and I have come to some really hard fought conclusions. First of all, whatever coding standard you implement, be consistent. That way if you discover a problem with the way you are doing things, it will be consistently wrong. I recently ran into a problem that was extremely difficult to track down but it was resulting in a stack corruption. After many hours of going bleary eyed trying to read my over 500,000 lines of code I resorted to a third party code checker. One of my problems was the 'just in time' variable declaration approach. I never expected to find that if you declare a variable within a code block such as an if or a switch that the variable would go out of scope later on. While this was not my only problem it did contribute to my issue. Secondly, I have had many programmers working for me over the years and have found that the KISS principle really applies here. If I allowed my programmers to code any way that they want, I can't support the code. If I insist that the coding, variable declarations, variable naming convention etc all be done in a certain way, then it can be maintained by multiple programmers. For this reason alone, I am an ardant supporter of declaring variables at the top of a function. You may be asking how I ended up with JIT declarations then? Simple answer, other peoples code. 'With hurricanes, tornados, fires out of control,mud slides, flooding, severe thunderstorms tearing up the country! from one end to another, and with the threat of bird flu and terrorist attacks, are we sure this is a good time to take God out of the Pledge of Allegiance?' - Jay Leno

[chaiguy1337]

Just because there is a new feature doesn't mean it's necessarily better. There have been mistakes made in the past with "new features". In this particular case, however, I agree with you.

“Time and space can be a bitch.” –Gushie, Quantum Leap {o,o}.oO( Want a great RSS reader? Try FeedBeast! ) |)””’) -”-”-

[Dan Neely]

Does being hoisted on its own petard count?

Otherwise [Microsoft is] toast in the long term no matter how much money they've got. They would be already if the Linux community didn't have it's head so firmly up it's own command line buffer that it looks like taking 15 years to find the desktop. -- Matthew Faithfull

[chaiguy1337]

Timothy W. Okrey wrote:

I never expected to find that if you declare a variable within a code block such as an if or a switch that the variable would go out of scope later on.

Well this is simply a case of being uneducated about the rules of the language you were using. I could argue that I never expected: int main( void ) { MakeAwesomeProgram(); } ...to not create the world's awesomest program, but chances are it's not going to. The rules of scope declaration are quite sound: a variable is only good in the scope it's defined in. In fact, you can even use a rarely-seen technique for defining arbitrary blocks of scope solely for this purpose: { int i = 5; ... } { int i = 10; // different 'i' ... }

“Time and space can be a bitch.” –Gushie, Quantum Leap {o,o}.oO( Want a great RSS reader? Try FeedBeast! ) |)””’) -”-”-

[Ravi Bhavnani]

That would be an uplifting experience. :) /ravi

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