proxy.golang.org : github.com/itzg/go-flagsfiller

Package flagsfiller makes Go's flag package pleasant to use by mapping the fields of a given struct into flags in a FlagSet. A FlagSetFiller is created with the New constructor, passing it any desired FillerOptions. With that, call Fill, passing it a flag.FlatSet, such as flag.CommandLine, and your struct to be mapped. Even a simple struct with no special changes can be used, such as: After calling Parse on the flag.FlagSet, the corresponding fields of the mapped struct will be populated with values passed from the command-line. For an even quicker start, flagsfiller provides a convenience Parse function that does the same as the snippet above in one call: By default, the flags are named by taking the field name and performing a word-wise conversion to kebab-case. For example the field named "MyMultiWordField" becomes the flag named "my-multi-word-field". The naming strategy can be changed by passing a custom Renamer using the WithFieldRenamer option in the constructor. Additional aliases, such as short names, can be declared with the `aliases` tag as a comma-separated list: FlagSetFiller supports nested structs and computes the flag names by prefixing the field name of the struct to the names of the fields it contains. For example, the following maps to the flags named remote-host, remote-auth-username, and remote-auth-password: To declare a flag's usage add a `usage:""` tag to the field, such as: Since flag.UnquoteUsage normally uses back quotes to locate the argument placeholder name but struct tags also use back quotes, flagsfiller will instead use [square brackets] to define the placeholder name, such as: results in the rendered output: To declare the default value of a flag, you can either set a field's value before passing the struct to process, such as: or add a `default:""` tag to the field. Be sure to provide a valid string that can be converted into the field's type. For example, FlagSetFiller also includes support for []string fields. Repetition of the argument appends to the slice and/or an argument value can contain a comma or newline separated list of values. For example: results in a three element slice. The default tag's value is provided as a comma-separated list, such as FlagSetFiller also includes support for map[string]string fields. Each argument entry is a key=value and/or repetition of the arguments adds to the map or multiple entries can be comma or newline separated in a single argument value. For example: results in a map with three entries. The default tag's value is provided a comma-separate list of key=value entries, such as FlagSetFiller also supports following field types: - net.IP: format used by net.ParseIP() - net.IPNet: format used by net.ParseCIDR() - net.HardwareAddr (MAC addr): format used by net.ParseMAC() - time.Time: format is the layout string used by time.Parse(), default layout is time.DateTime, could be overriden by field tag "layout" - slog.Level: parsed as specified by https://pkg.go.dev/log/slog#Level.UnmarshalText, such as "info" To activate the setting of flag values from environment variables, pass the WithEnv option to flagsfiller.New or flagsfiller.Parse. That option takes a prefix that will be prepended to the resolved field name and then the whole thing is converted to SCREAMING_SNAKE_CASE. The environment variable name will be automatically included in the flag usage along with the standard inclusion of the default value. For example, using the option WithEnv("App") along with the following field declaration would render the following usage: To override the naming of a flag, the field can be declared with the tag `flag:"name"` where the given name will be used exactly as the flag name. An empty string for the name indicates the field should be ignored and no flag is declared. For example, Environment variable naming and processing can be overridden with the `env:"name"` tag, where the given name will be used exactly as the mapped environment variable name. If the WithEnv or WithEnvRenamer options were enabled, a field can be excluded from environment variable mapping by giving an empty string. Conversely, environment variable mapping can be enabled per field with `env:"name"` even when the flagsfiller-wide option was not included. For example, This file implements support for all types that support interface encoding.TextUnmarshaler

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purl: pkg:golang/github.com/itzg/go-flagsfiller
License: MIT
Latest release: 8 months ago
First release: over 5 years ago
Namespace: github.com/itzg
Dependent packages: 20
Dependent repositories: 25
Stars: 32 on GitHub
Forks: 9 on GitHub
Docker dependents: 34
Docker downloads: 385,317,276
See more repository details: repos.ecosyste.ms
Funding links: https://github.com/sponsors/itzg
Last synced: 13 days ago

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