WriteArray() (type)

Write a data type, one array element at a time

Description

This is a function you would write when programming a Murex data-type.

It’s called by builtins to allow them to write data structures one array element at a time.

The purpose of this function is to allow builtins to support sequential writes (where possible) and also create a standard interface for builtins, thus allowing them to be data-type agnostic.

A Collection of Functions

WriteArray() should return a struct that satisfies the following interface{}:

package stdio

// ArrayWriter is a simple interface types can adopt for buffered writes of formatted arrays in structured types (eg JSON)
type ArrayWriter interface {
    Write([]byte) error
    WriteString(string) error
    Close() error
}

Usage

Registering your WriteArray()

// To avoid confusion, this should only happen inside func init()
stdio.RegisterWriteArray(/* your type name */, /* your writeArray func */)

Examples

Example WriteArray() function:

package string

import (
    "github.com/lmorg/murex/lang/stdio"
)

type arrayWriter struct {
    writer stdio.Io
}

func newArrayWriter(writer stdio.Io) (stdio.ArrayWriter, error) {
    w := &arrayWriter{writer: writer}
    return w, nil
}

func (w *arrayWriter) Write(b []byte) error {
    _, err := w.writer.Writeln(b)
    return err
}

func (w *arrayWriter) WriteString(s string) error {
    _, err := w.writer.Writeln([]byte(s))
    return err
}

func (w *arrayWriter) Close() error { return nil }

Detail

Since not all data types will be stream-able (for example json), some types may need to cache the array and then to write it once the array writer has been closed.

package json

import (
    "github.com/lmorg/murex/lang/stdio"
    "github.com/lmorg/murex/utils/json"
)

type arrayWriter struct {
    array  []string
    writer stdio.Io
}

func newArrayWriter(writer stdio.Io) (stdio.ArrayWriter, error) {
    w := &arrayWriter{writer: writer}
    return w, nil
}

func (w *arrayWriter) Write(b []byte) error {
    w.array = append(w.array, string(b))
    return nil
}

func (w *arrayWriter) WriteString(s string) error {
    w.array = append(w.array, s)
    return nil
}

func (w *arrayWriter) Close() error {
    b, err := json.Marshal(w.array, w.writer.IsTTY())
    if err != nil {
        return err
    }

    _, err = w.writer.Write(b)
    return err
}

See Also

This document was generated from lang/stdio/interface_doc.yaml.

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Last built on Tue Dec 10 22:56:57 UTC 2024 against commit 60f05a260f05a227caf73dd5b3478e3cb3f4bb24e46745b.

Current version is 6.4.1005 (develop) which has been verified against tests cases.