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Fixed Location of DLL

Posted on 2002-03-18
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Last Modified: 2010-04-05
In a lot of programs I have seen where the program keeps all the DLL's in a certain directory and all other programs refference those DLL's from that directory (Not current dir, Not System or System32 dir! i.e. C:\PROGRAM FILES\VENDOR\PROGRAM\MODULE1\MODULE.EXE reads LIBRARY1.DLL from C:\PROGRAM FILES\VENDOR\LIBRARIES\LIBRARY1.DLL)

How do you do this? At work we have our product that uses a couple of DLL's and currently the only way we have found to be sure that all programs have access to the DLL is to put a copy in each directory (I know it's a bad idea! But since my sup refuses to let us tell the clients to install the program on each workstation, instead just install it once and map a shared folder for everyone who uses the program) it's the best option we've found.

If someone has an idea, I'm all ears. BTW, it cannot be absolute path requirements unless you can also provide a way to obtain the absolute directory the program is run from.

Thanks!
-- Dan
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Question by:DanEgli
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by:SteveWaite
ID: 6878800
search relative to your exe
Handle := LoadLibrary(Application.ExeName + '\mydlls\' +  MyDllName);

or add the dll path to the PATH env. variable.

Regards,
Steve




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by:DanEgli
ID: 6878835
Oh... So then first question is what is handle? (handle := ??), next, is that static or dynamic loading? I'd prefer static loading (i.e. program starts up, and if it's missing a dll it says so and quits). Third. Since you are using a kind of Handle do I need to call procedure/functions like Handle.Foo(a,b,c); or is it just Foo(a,b,c);??

Thanks!
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SteveWaite earned 50 total points
ID: 6878975
the dynamic loading shown goes to any required directory
static loading

procedure DoSomething; external 'MYLIB.DLL';// dllpath
needs the path in there alrweady..

dynamic loading gives you the chance to set the path..

var
  dllpathv: String;
  dllHandle: THandle;
  MyFunc: function;

// e.g. in create
dllHandle := LoadLibrary(dllpath);
if not (dllHandle = 0)
  then @MyFunc := GetProcAddress(dllHandle, 'MydllFunc'); //etc.

// e.g. in destroy
if not (dllHandle = 0)
  then FreeLibrary(dllHandle);

Steve

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Expert Comment

by:SteveWaite
ID: 6878979
should say..
needs the path in there already..
and..
var
 dllpath: String;
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Author Comment

by:DanEgli
ID: 6879099
so for a static load that would place the dll in, say, ..\libs\mylib.dll, calling procedure Foo, it would be like this?

procedure Foo(a,b,c : string) ; External '..\libs\mylib.dll';

This correct?

Thanks!
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Expert Comment

by:AvonWyss
ID: 6879203
Another possibility is to add it to the shared DLL's of the system. It is then found automatically, without the need to link it "hard" in the EXE file.

The following registry key holds the pasths to DLL's:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\SharedDLLs
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Expert Comment

by:SteveWaite
ID: 6889644
cheers dan
I think you will find the dll will get added automatically to the regkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\SharedDLLs
after it's been used once.

Regards,
Steve
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