[JustBored]

https://sampforum.blast.hk/showthread.php?tid=441293
The idea is simple:

pawn Код:

<function>()
{
    <chained call>();
}
<does a hook exist?>
    <yes - remove the old one>
<else>
    <no - it does now>
<end>
<rename chain>
<forward the function>

An example:

pawn Код:

public OnPlayerConnect(playerid)
{
    #if defined MyLib_OnPlayerConnect
        MyLib_OnPlayerConnect(playerid);
    #endif
    return 1;
}
#if defined _ALS_OnPlayerConnect
    #undef OnPlayerConnect
#else
    #define _ALS_OnPlayerConnect
#endif
#define OnPlayerConnect MyLib_OnPlayerConnect
#if defined MyLib_OnPlayerConnect
    forward MyLib_OnPlayerConnect(playerid);
#endif