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| # Repeats |
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| In many cases, there is a need to periodically execute some code. |
| While you can create and manage threads to achieve the same effect, there are already functions to factilitate just that: |
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| **MapGameTimeRepeat(*name*, *interval*, *func*)** |
| : Declares a repeating function *func* which will be called every *interval* milliseconds of *GameTime* while there is a map loaded. |
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| **MapRealTimeRepeat(*name*, *interval*, *func*)** |
| : Declares a repeating function *func* which will be called every *interval* milliseconds of *RealTime* while there is a map loaded. |
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| The function *func* receives as parameter the time from the previous invocation. On the first invocation it receives *nil* as parameter. |
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| *func* can return a value which will be used (one time only) as sleep time before the next invocation instead of the *interval* provided. |
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| !!! WARNING |
| If *interval* is zero or a negative number *func* will be called in a loop without any delay. In that case it **must** sleep otherwise it will freeze the entire game. |
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| Since *func* runs in its own thread it can sleep or wait for wakeup or wait for messages. You can easily wakeup a repeat function: |
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| **WakeupPeriodicRepeatThread(*name*, ...)** |
| : Wakes up the thread of the periodic repeat with *name*. To have an effect, the repeat function *func* should have called *WaitWakeup()*. |
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| Repeats have several advantages: |
| - after lua reload, the new *func* is called instead of the old one |
| - after loading a savegame created with an old repeat func the new func gets called instead |
| - when loading a savegame created before the repeat was introduced in the code, the repeat is started |
| - the repeat is started on entering a map and stopped it when exiting the map |
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| # Examples |
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| Update the daily quest once a day. In this case, we know the map starts at 6am, |
| so we use the first invocation when *interval* is *nil* to sleep 6 more hours |
| and then call *UpdateDailyQuest()* exactly at 12h every day thereafter. |
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| ~~~~~~~~~~ Lua |
| MapRealTimeRepeat("", const.HourDuration * 24, function (interval) |
| if not interval then |
| return const.HourDuration * 6 -- sleep 6h on the first invocation |
| end |
| UpdateDailyQuest() |
| end) |
| ~~~~~~~~~~ |
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| If updating the UI is slow, it can be done in a thread after *UpdateUI* is called |
| but no more often than once every 100ms: |
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| ~~~~~~~~~~ Lua |
| MapVar("UIUpdatePending", false) |
| MapRealTimeRepeat("UpdateUI", 100, function (interval) |
| if not UIUpdatePending then WaitWakeup() end |
| UIUpdatePending = false |
| UpdateUIForReal() |
| end) |
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| function UpdateUI() |
| UIUpdatePending = true |
| WakeupPeriodicRepeatThread("UpdateUI") |
| end |
| ~~~~~~~~~~ |
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