Write array

Purpose: Store value into an array.

 write-array <array> \
     key <key> \
     value <value> \
     [ old-value <old value> ]

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write-array will store a <value> (in "value" clause) under index <key> (in "key" clause) into <array>, which must be created with new-array. <key> is a number from 0 up to (excluding) the currently allocated array size (see new-array). The type of <value> is determined when <array> is created (see "type" clause), and can be either a string, number or a boolean.

<key> and <value> are collectively called an "element".

The old value associated under index <key> is returned in <old value> (in "old-value" clause) and <value> will replace the old value.

If an <array> was created with "process-scope" clause (see new-array), then the element <value> will not be freed when the current request ends, rather it will persist while the process runs, unless deleted (see read-array with delete clause).

Examples

Writing data to an array:

 new-array arr
 write-array arr key 100 value "some data"

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Writing new value with the same key index and obtaining the previous value (which is "some data"):

 write-array arr key 100 value "new data" old-value od
 @Previous value for this key index is <<print-out od>>

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The following is an array service, where a process-scoped array is created. It provides inserting, deleting and querying indexed keys. Maximum number of keys it holds is 10,000,000 (indexed from 0 to 9,999,999). Such a service process can run indefinitely. Create file arrsrv.golf:

 %% /arrsrv public
     do-once
     new-array arr max-size 10000000 process-scope type string
     end-do-once

     // Get input parameters
     get-param op
     get-param key
     get-param data
     // Convert string keye to number
     string-number key to key_n

     if-true op equal "add" // Add data to array
         write-array arr key key_n value data old-value old_data
         delete-string old_data
         @Added [<<print-out key>>]
     else-if op equal "delete" // Delete data and obtain the value deleted
         read-array arr key key_n value val delete
         @Deleted [<<print-out val>>]
         delete-string val
     else-if op equal "query" // Query hash based on key value
         read-array arr key key_n value val
         @Value [<<print-out val>>]
     end-if
 %%

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Create and make the application, then run it as service:

// Create application
gg -k arr
// Make application
gg -q
// Start application (single process key service)
mgrg -w 1 arr

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Try it from a command line client (see gg):

// Add data
gg -r --req="/arrsrv/op=add/key=15/data=15" --service --app="/arr" --exec
// Query data
gg -r --req="/arrsrv/op=query/key=15" --service --app="/arr" --exec
// Delete data
gg -r --req="/arrsrv/op=delete/key=15" --service --app="/arr" --exec

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See read-array for more examples.