[fpc-devel] "Blank slate" next version of FPC

[Giuliano Colla]

Il 20/02/2019 19:11, Nikolai Zhubr ha scritto:

> Now it is getting even more curious. Admittedly I don't use C too much 
> (and C++ even less so, approximately never), maybe that is why I do 
> not understand your reasoning. Could you maybe give an example of such 
> problematic inline declaration and its negative effect, in C++ at 
> least? Honestly I can't imagine any.

Very easy: you read your code written some time before, or someone 
else's code, you miss the inline declaration, because it's buried in the 
code, and you mistake the variable with another one previously declared, 
in the outer scope.

I have just met such a situation: I ported from C++ to Pascal an 
algorithm for the computation of the kinematics of a Delta Robot, and I 
was badly bitten.
In that case you are just dealing with X,Y,Z coordinates, and 
Theta0,Theta1,and Theta2 angles, and you find, in the body of a 
procedure, some X,Y,Z or Theta which have global scope, and some which 
are just local to some smaller (but not too small) block and which are 
redeclared inline. Rather hard to tell them apart.
Redeclaring inline an index I, which you'll be then using a lot of 
times, is the best way to shoot you in the feet. Pascal encourages you 
to use I,J,K at first, then ii,jj,kk etc.

Moreover, using a modern tool such as Lazarus, you never need to scroll 
1000 lines to find a declaration: you just press alt+Up to go to the 
declaration of the symbol over the cursor, and Ctrl+H to go back to the 
line of code.

Keeping all declarations separated from code is just good programming 
practice. Mixing declaration and code is bad programming practice, IMO, 
and I appreciate Pascal for not supporting it.

Giuliano

-- 
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