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A.M. Hoornweg

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Everything posted by A.M. Hoornweg

  1. I think it does. The two searches are not disjoint, so calling StringReplace (shortest word first) would replace "Hut" by "House" and the name "Hutt" would not exist anymore in the second search pass due to this insertion. An approach that starts by scanning the original string for all search terms would reveal two "hits" at the first letter H and then things get interesting, because it would have to decide which replacement is "better". So it needs some rules to make that decision. One rule could be to replace the longest search term.
  2. What I mean is, if you call Embarcadero's stringReplace routine multiple times, then each subsequent replace sees the insertions made by the previous call. But if you write a MultiStringReplace routine that first analyzes the string and determines everything that is to be replaced, that is not the case. It sees only the original string and not the intermediate insertions. The end result may be different.
  3. I am a bit puzzled here. How do you want to guarantee a consistent outcome? The first "search & replace" will change the string. It will remove characters and insert new ones. Which may get captured by the next search. Suppose you have a string like "Jabba the Hutt lived in a Hut" and you want to replace "Hutt" by "Alien" and "Hut" by "House". How do you decide which replacement to do first?
  4. A.M. Hoornweg

    50 Years of Pascal

    Do you mean units? Units only came in Turbo Pascal 4 AFAIK.
  5. Hello all, in my quest to port a very large project -containing dozens of COM DLL's- from Delphi XE to Sydney, the main obstacle for me was the exploding executable size. Each and every DLL in my project group had grown between 1-4 megabytes and that really added up painfully. Most of that growth, of course, is due to the new extended RTTI (which I do not use). The project was already huge before, and a doubling or tripling in size would cause deployment problems (the software is used on oil wells on remote locations and bandwidth is often costly and slow). Trying to strip off some MB's wherever I could, I started studying the MAP files to make sure no unnecessary stuff was linked in. I noticed that all of my non-visual COM DLL's nevertheless pull in huge chunks of the visual VCL, including units VCL.Forms, VCL.Themes, VCL.Imagelist etc. I am absolutely sure that I don't use these routines anywhere and still they make up over 60% of the executable's code! The underlying cause is that all of the xxxx_TLB.PAS files, which the IDE auto-generates, use a unit called OleServer which has an initialization section. No code in the unit itself is called, but the initialization section manages to pull in most of the VCL for whatever reason. As a test, I made a dummy unit "oleserver.pas" and referenced it as the first file in my COM DLL applications. The project compiled fine, and this change alone instantly reduced executable size with a whopping 1 MB. And the best thing, the project still worked as expected. So it seems to me that this whole OleServer unit is an unnecessary thing in my projects. Another thing. When I link my projects against a "stripped" version of the RTL/VCL (recompiled without extended RTTI), the size difference becomes astronomic. My DLL's have now typically lost 80% of their size, going from 2MB+ to only 400kb. With these executable size reductions I am finally able to port this project to Delphi Sydney. I am in the process of writing a tool to automate the "rtti stripping" of the RTL/VCL which I plan to release as open source. For example, projects like "inno setup" might benefit from it.
  6. I'll do that (create the QP), thank you. (edit) https://quality.embarcadero.com/browse/RSP-33241
  7. To each his own. For single-exe projects it is a non-issue and I wouldn't bother either if my project consisted of only a handful of modules.
  8. I haven't ported the project group from XE to Sydney yet, for now the directive is needed for XE where it applies to all units that the compiler rebuilds. I just wish Embarcadero had optimized RTTI for size from the very beginning and given us the choice wether to use it at all. Having RTTI in your code offers possible attack vectors for reverse engineering etc.
  9. I use a RTTI-stripped version of the XE libraries since ages, because when I migrated from Delphi 2009 to XE my executable sizes also grew a lot. That RTTI stripping is much easier to achieve with XE because the {$RTTI....} directive was still a global option then, so you don't need to patch any source files. Stripping RTTI is now an integral part in my Finalbuilder build scripts. Edit: I have attached an image with the executable sizes. All executables were compiled in "release mode" without any debugging info. All executables were compiled with {$WEAKLINKRTTI ON} and {$RTTI EXPLICIT METHODS([]) PROPERTIES([]) FIELDS([])} in the DPR. (1) Compiled with XE10.4.2 Sydney. (2) As (1), replaced unit "Oleserver" with a dummy unit so no unnecessary VCL code is pulled in. (3) As (2), using a RTTI-Stripped RTL/VCL. (4) Compiled with Delphi XE, replaced unit "Oleserver" with a dummy unit so no unnecessary VCL code is pulled in. (5) As (4), using a RTTI-Stripped RTL/VCL.
  10. A.M. Hoornweg

    spinlock primitives

    The purpose of a spinlock is to obtain the lock as quickly as possible. On a single core system, doLock should yield on contention because the thread that owns the lock is waiting to be resumed. On multi-core systems it can keep spinning. In the initialization of the unit, call GetProcessAffinityMask() and count the bits in the integer to obtain the number of cores available to the program.
  11. A.M. Hoornweg

    spinlock primitives

    One problem I see is that on a single-core CPU, doLock will burn up all remaining CPU time of the time slice on contention.
  12. Hello all, I see that Delphi supports both bitwise and logical versions of and/or/xor operator overloading, but I'm not 100% sure about the difference between the two concepts. Assume I have a certain record type, and that I want to implement "AND", "OR" and "XOR" operators, each resulting in some kind of merge of the original input records. The syntax I would like to use in my code would simply be "A:=(B OR C);" Do I need to implement BitWiseOr etc or LogicalOr, and if I implement both, how does Delphi decide which of the two is going to be used?
  13. A.M. Hoornweg

    class operator, AND/OR/XOR question

    I did consult the wiki but somehow managed to skip this line of text ten times. It must be monday morning .... Thanks for pointing it out!
  14. Hello all, is there a way to quickly initialize all local variables of a procedure with zero, maybe using FillChar? It would be very practical to use at the beginning of a procedure. I had a case recently where the Delphi compiler didn't throw a warning when I accessed a local variable before it had been initialized and it had me debugging for hours.
  15. A.M. Hoornweg

    Quickly zero all local variables?

    Generally, yes. But it would also be great to have a nifty tool at my disposal that lets me wipe all locals on the stack with a single call, especially if it is a complex routine with lots and lots of local vars. In such cases it would simply save a lot of boilerplate code. Delphi does the very same thing for class members and I would totally hate it if it didn't. I had hoped that this would be a trivial thing to write, since all StdCall procedures start with a byte sequence like "mov ebp,esp; add esp, -sizeof(localvars)".
  16. A.M. Hoornweg

    Quickly zero all local variables?

    Normally yes. I only asked because I overlooked initializing a certain local variable and the compiler (Delphi XE, which is used in that specific project) didn't warn me. OTOH, if Delphi takes the trouble to zero-fill managed local variables anyway, it puzzles me why it does not simply fill the rest as well. A REP STOSD is lightning fast.
  17. A.M. Hoornweg

    Quickly zero all local variables?

    It seems to vary with compiler versions. I use both XE and Sydney.
  18. A.M. Hoornweg

    Hashing Street Addresses ?

    Can you use the postal code to identify the town and street? In the Netherlands we have a system where the postal code combined with the house nr uniquely identifies an address. For example, enter "Netherlands 2594 BD 10" in google Maps and you'll see where our king lives.
  19. A.M. Hoornweg

    The Case of Delphi Const String Parameters

    The reason is, that when S goes out of scope, it decrements the reference count of G. G should only be destroyed when its reference count reaches zero so that action must be atomic.
  20. A.M. Hoornweg

    The Case of Delphi Const String Parameters

    That may very well be true. But when a developer is doing refactoring to make code more legible and concise, IMHO it is a good thing if the parameter list reflects the intended use of the parameters. So if a parameter is intended just for outputting something and not for modifying an existing value, the "out" modifier is clearer than "var". I find "const" parameters confusing at times, especially when passing stuff like arrays. If I pass an array as a const, am I supposed to be able to modify elements or not? The Delphi documentation (link at he bottom) says "... constant parameters are similar to value parameters, except that you cannot assign a value to a constant parameter within the body of a procedure or function..." . I don't want to nit-pick, but I find it very confusing and counter-intuitive that I can modify the array in such a case. Type tintarray=tarray<integer>; Procedure dosomething (CONST a:tintarray); var i:integer; begin for i:=0 to high(a)-1 do a[i]:=random(maxint); end; procedure TForm1.Button1Click(Sender: TObject); var x:tintarray; begin setlength(x,10); //newly allocated space is set to 0 dosomething(x); showmessage(format('%d',[x[0]])); end; http://docwiki.embarcadero.com/RADStudio/Sydney/en/Parameters_(Delphi)#Constant_Parameters
  21. A.M. Hoornweg

    The Case of Delphi Const String Parameters

    Unlike "shortstring", Delphi cannot pass managed types such as strings by value. It is always a pointer. I'm not 100% sure but I think an "out" parameter is like a "promise" to return a value no matter what, and also a promise not to use it for input. The problem being that it is possible to pass the same variable twice and thus circumvent the no-input promise.
  22. A.M. Hoornweg

    The Case of Delphi Const String Parameters

    "Out" parameters of managed types (such as strings, interfaces, dynamic arrays) are initialized before a method is called. The problem only arises because multiple parameters in the method reference the same string. The behavior is correct but very counter-intuitive. It would behave more intuitively if the compiler would issue a UniqueString() for the second/identical parameter.
  23. A.M. Hoornweg

    The Case of Delphi Const String Parameters

    I posted about it before in this forum and was told that it's intended behavior. Admittedly, it's a corner case, but it did happen and cost me a lot of time to figure it out. A compiler warning would have been nice.
  24. A.M. Hoornweg

    grid with expandable area below each row?

    There's also this thingy called "tGridpanel" in Delphi. I have never used it myself though.
  25. A.M. Hoornweg

    From Interbase To Firebird

    How about metadata (access rights) , triggers etc?