Old 01-18-2019, 05:48 AM   #1
andyp24
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Default Read and write from file on disk

Hi

Is it possible (I presume it must be?) to allow a Reaper script to create, write to, read from and delete a small file on the hard disk?

I can think of some uses for this, such as storing the state of an array or variable in a file (somehow! not sure of what form the data would need to take) so that a script can run multiple times, but always make decisions based on the state of events when it was run the first time.

There may be another way to do this, but any pointers/resources would be welcome.

Thanks
Andy
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Old 01-18-2019, 05:58 AM   #2
cfillion
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Yes, all ReaScripts (Lua, Python and ELL) can read and write files (except if run with restricted permissions).

https://www.lua.org/manual/5.3/manual.html#6.8
https://www.lua.org/manual/5.3/manua...#pdf-os.remove

There's also REAPER's temporary, permanent and project extstates.

Last edited by cfillion; 01-18-2019 at 06:06 AM.
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Old 01-18-2019, 06:29 AM   #3
andyp24
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Ok, ExtState sounds like it might be the way to go, as this is only for temporary use within an edit, and would never need to be recalled after the project was closed etc.

Is there a resource to learn about this please?

Thanks
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Old 01-18-2019, 06:39 AM   #4
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Search for "ExtState" in the ReaScript documentation (Help menu in REAPER). The functions are SetExtState, HasExtState, GetExtState and DeleteExtState. An extstate is identified by a section and key of your choice. The section is usually chosen to be unique to the script and the key to identify the data being stored. Set the "persist" argument to false in order to have the extstate stored only until REAPER is closed.
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Old 01-18-2019, 06:46 AM   #5
andyp24
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Yeah, I see them in the API documentation, but as someone very new to scripting of any kind, I was hoping for an idiot's guide :-)

I guess I'll just experiment and see what I can make it do.

Thanks
Andy
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Old 01-18-2019, 07:54 AM   #6
X-Raym
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You should consider inspecting already made script, you have tons of exemple of file reading and exporting there :P

Also check sitepoint tutorial about Lua I/O, very well done doc.
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Old 01-18-2019, 08:02 AM   #7
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I will, thanks - not at my Reaper setup right now though.

But how do I know which scripts to look at? :-)

Thanks for the other suggestion too.

Andy
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Old 01-18-2019, 09:34 AM   #8
Meo-Ada Mespotine
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Toy around with them.

Type in the function and put into the parameters, what they expect. If they fail, they will tell you that and you can learn from that.

In your case: try to set(reaper.SetExtState) an extstate and successfully get it(reaper.GetExtState).

like:

my_new_extstate_section = "sectionname"
my_new_extstate_key = "keyname"
my_new_extstate_value = "I am the value. Try to get or I will feel abondaned in here."

reaper.SetExtState(my_new_extstate_section, my_new_extstate_key, my_new_extstate_value, false)

extstate_value = reaper.GetExtState("sectionname", "keyname")


Toy around with it, until it does, what you want and move on to the next step. And don't be afraid of mistakes. This is the fastest way of learning the basics of ReaScript and Lua.


A great resource is also X-Raym's tutorial on ReaScript:

https://www.extremraym.com/en/reascript-basics-part1/
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Old 01-18-2019, 09:52 AM   #9
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Thanks mespotine

I will do just that - try some very simple scripts that do nothing but read and write various things to and from ExtState until I figure it out...

And thanks for the other recommendation, but already 99% of everything I know about ReaScript comes from X-Raym's video series :-)

That's what got me started and convinced me I might actually be able to understand enough to do something useful with it!

Andy
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Old 01-18-2019, 09:55 AM   #10
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So then, browse through the scripts, that you can download via ReaPack. There are many of them and they are good
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