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Version: v7.1.0

open/3

Description​

open/3 is a predicate which opens a stream to a source or sink. This predicate is a shorthand for open/4 with an empty list of options.

Signature​

open(+SourceSink, +Mode, -Stream)

where:

  • SourceSink is an atom representing the source or sink of the stream, which is typically a URI.
  • Mode is an atom representing the mode of the stream to be opened. It can be one of "read", "write", or "append".
  • Stream is the stream to be opened.

open/3 gives True when SourceSink can be opened in Mode.

Examples​

Open a resource for reading​

This scenario showcases the procedure for accessing a resource stored within a CosmWasm smart contract for reading purposes and obtaining the stream's properties.

See the open/4 predicate for a more detailed example.

Here's the steps of the scenario:

  • Given the CosmWasm smart contract "okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht" and the behavior:
message: |
  {
    "object_data": {
      "id": "4cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05"
    }
  }
response: |
  Hello, World!
  • Given the query:
open(
  'cosmwasm:storage:okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht?query=%7B%22object_data%22%3A%7B%22id%22%3A%20%224cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05%22%7D%7D&base64Decode=false',
  read,
  _
).
  • When the query is run
  • Then the answer we get is:
height: 42
gas_used: 2223
answer:
  has_more: false
  variables:
  results:
  - substitutions: