README
¶
colorwriter Package
Thin wrapper that returns a color-profile-aware
io.Writerfor terminal output, with a no-op stub for wasm builds.
Overview
The colorwriter package provides a factory for io.Writer values that adapt ANSI color output based on the current environment. On non-wasm platforms it wraps the given writer with github.com/charmbracelet/colorprofile so that NO_COLOR, COLORTERM, and terminal capability are consulted automatically. On wasm (js / wasm build tags) the package returns the writer unchanged, since color-profile detection is not supported on that platform.
It is imported by pkg/console and pkg/logger to obtain consistent stdout/stderr writers and to degrade already-rendered ANSI strings when output helpers must return a string instead of writing directly.
Public API
| Symbol | Signature | Description |
|---|---|---|
New |
func(w io.Writer, environ []string) io.Writer |
Returns a color-profile-aware writer wrapping w using environ (e.g. os.Environ()) to detect NO_COLOR, COLORTERM, and terminal capabilities. On wasm, returns w unchanged. |
Stderr |
func() io.Writer |
Convenience wrapper that calls New(os.Stderr, os.Environ()). On wasm, returns os.Stderr directly. |
Stdout |
func() io.Writer |
Convenience wrapper that calls New(os.Stdout, os.Environ()). On wasm, returns os.Stdout directly. |
Degrade |
func(s string, environ []string) string |
Routes a pre-rendered ANSI string through a color-profile-aware writer backed by a string builder, downgrading or stripping ANSI according to environ. On wasm, returns s unchanged. |
Build variants
| Build constraint | Behavior |
|---|---|
!js && !wasm (colorprofile_writer.go) |
New delegates to colorprofile.NewWriter; Stderr and Stdout wrap the corresponding standard streams with the process environment; Degrade transforms a rendered ANSI string through an in-memory color-profile-aware writer. |
js || wasm (colorprofile_writer_wasm.go) |
New returns w unchanged; Stderr and Stdout return the corresponding standard streams directly; Degrade returns the original string unchanged. Color-profile detection is not supported on wasm. |
Usage Examples
import (
"os"
"github.com/github/gh-aw/pkg/colorwriter"
)
// Wrap an arbitrary writer (e.g. for tests or piped output).
w := colorwriter.New(os.Stderr, os.Environ())
fmt.Fprintln(w, "styled output respects NO_COLOR and terminal capabilities")
// Obtain a ready-to-use stderr writer.
stderr := colorwriter.Stderr()
fmt.Fprintln(stderr, "styled output to os.Stderr")
// Degrade a rendered ANSI string before returning it to a stdout caller.
plain := colorwriter.Degrade("\x1b[31mwarning\x1b[0m", []string{"NO_COLOR=1", "TERM=xterm-256color"})
fmt.Println(plain)
Dependencies
External:
github.com/charmbracelet/colorprofile— color-profile detection and ANSI downgrading (non-wasm builds only)
Source-verified export coverage
This appendix is generated from the current non-test Go source files in this package and records any exported top-level symbols that are not already described above.
| Category | Count |
|---|---|
| Types | 0 |
| Constants | 0 |
| Variables | 0 |
| Functions and methods | 4 |
| Additional symbols documented in this appendix | 0 |
The sections above already mention every exported top-level symbol in the current source tree.
This specification is automatically maintained by the spec-extractor workflow.
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Degrade ¶ added in v0.82.13
Degrade returns s with ANSI sequences downgraded (or stripped) according to the current process environment (NO_COLOR, COLORTERM, TERM). It is intended for use with string-returning format helpers: render the style first, then call Degrade so that the caller's output honors the color profile.
func New ¶
New returns an io.Writer that adapts color output based on the provided environment variables (e.g. NO_COLOR, COLORTERM, TERM).
Types ¶
This section is empty.
Source Files