Local Handle Vars

From WarCraft3

The Local Handle Variables (LHV) script is a major milestone in the evolution of modern Jass. It allowed easy attachment of anything to any handle on the map.

Contents 1 Code 1.1 Local Handle Variables by KaTaNNa 2 Why LHV was originally used 3 Why LHV is Deprecated

Code

Local Handle Variables by KaTaNNa

// ===========================
function H2I takes handle h returns integer
    return h
    return 0
endfunction

// ===========================
function LocalVars takes nothing returns gamecache
    // Replace InitGameCache("jasslocalvars.w3v") with a global variable!!
    return InitGameCache("jasslocalvars.w3v")
endfunction

function SetHandleHandle takes handle subject, string name, handle value returns nothing
    if value==null then
        call FlushStoredInteger(LocalVars(),I2S(H2I(subject)),name)
    else
        call StoreInteger(LocalVars(), I2S(H2I(subject)), name, H2I(value))
    endif
endfunction

function SetHandleInt takes handle subject, string name, integer value returns nothing
    if value==0 then
        call FlushStoredInteger(LocalVars(),I2S(H2I(subject)),name)
    else
        call StoreInteger(LocalVars(), I2S(H2I(subject)), name, value)
    endif
endfunction

function SetHandleBoolean takes handle subject, string name, boolean value returns nothing
    if value==false then
        call FlushStoredBoolean(LocalVars(),I2S(H2I(subject)),name)
    else
        call StoreBoolean(LocalVars(), I2S(H2I(subject)), name, value)
    endif
endfunction

function SetHandleReal takes handle subject, string name, real value returns nothing
    if value==0 then
        call FlushStoredReal(LocalVars(), I2S(H2I(subject)), name)
    else
        call StoreReal(LocalVars(), I2S(H2I(subject)), name, value)
    endif
endfunction

function SetHandleString takes handle subject, string name, string value returns nothing
    if value==null then
        call FlushStoredString(LocalVars(), I2S(H2I(subject)), name)
    else
        call StoreString(LocalVars(), I2S(H2I(subject)), name, value)
    endif
endfunction

function GetHandleHandle takes handle subject, string name returns handle
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction
function GetHandleInt takes handle subject, string name returns integer
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
endfunction
function GetHandleBoolean takes handle subject, string name returns boolean
    return GetStoredBoolean(LocalVars(), I2S(H2I(subject)), name)
endfunction
function GetHandleReal takes handle subject, string name returns real
    return GetStoredReal(LocalVars(), I2S(H2I(subject)), name)
endfunction
function GetHandleString takes handle subject, string name returns string
    return GetStoredString(LocalVars(), I2S(H2I(subject)), name)
endfunction

function GetHandleUnit takes handle subject, string name returns unit
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction
function GetHandleTimer takes handle subject, string name returns timer
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction
function GetHandleTrigger takes handle subject, string name returns trigger
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction
function GetHandleEffect takes handle subject, string name returns effect
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction
function GetHandleGroup takes handle subject, string name returns group
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction
function GetHandleLightning takes handle subject, string name returns lightning
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction
function GetHandleWidget takes handle subject, string name returns widget
    return GetStoredInteger(LocalVars(), I2S(H2I(subject)), name)
    return null
endfunction

function FlushHandleLocals takes handle subject returns nothing
    call FlushStoredMission(LocalVars(), I2S(H2I(subject)) )
endfunction

Why LHV was originally used

• It allowed users to avoid creating global variables (global variables had to be created in the Variable Editor prior to vJass).
• It made MUI much easier to achieve.
• LHV had relatively simple syntax with much functionality.

Why LHV is Deprecated

• As of Patch 1.23b, LHV will no longer compile.
• The huge lack of type-safety allows for amateur mappers to typecast any handle-extending type into another, which can cause crashes.
• LHV uses gamecache, a slow attachment method according to newer standards, and abuses the I2H version of the Return Bug, which can cause map instability.
• Because LHV avoided using global variables to store data, handle id's would be recycled, causing I2H to return the wrong handle after a variable was removed.
• The introduction of vJass allowed entire groups of data to be wrapped together in structs, allowing for easier attachment.

LHV can be easily replaced with hashtables.