Module: NRSER::Sys::Env

Defined in:
lib/nrser/sys/env.rb

Overview

Tools for dealing with the system (POSIX-like) environment.

Defined Under Namespace

Classes: Path

Constant Summary collapse

COMMON_EXPORT_NAMES =

Common and/or important ENV var names that we don’t really want to end up auto-generating.

Returns:

See Also:

Set[
  "ARFLAGS",
  "CC",
  "CDPATH",
  "CFLAGS",
  "CHARSET",
  "COLUMNS",
  "DATEMSK",
  "DEAD",
  "EDITOR",
  "ENV",
  "EXINIT",
  "FC",
  "FCEDIT",
  "FFLAGS",
  "GET",
  "GFLAGS",
  "HISTFILE",
  "HISTORY",
  "HISTSIZE",
  "HOME",
  "IFS",
  "LANG",
  "LC_ALL",
  "LC_COLLATE",
  "LC_CTYPE",
  "LC_MESSAGES",
  "LC_MONETARY",
  "LC_NUMERIC",
  "LC_TIME",
  "LDFLAGS",
  "LEX",
  "LFLAGS",
  "LINENO",
  "LINES",
  "LISTER",
  "LOGNAME",
  "LPDEST",
  "MAIL",
  "MAILCHECK",
  "MAILER",
  "MAILPATH",
  "MAILRC",
  "MAKEFLAGS",
  "MAKESHELL",
  "MANPATH",
  "MBOX",
  "MORE",
  "MSGVERB",
  "NLSPATH",
  "NPROC",
  "OLDPWD",
  "OPTARG",
  "OPTERR",
  "OPTIND",
  "PAGER",
  "PATH",
  "PPID",
  "PRINTER",
  "PROCLANG",
  "PROJECTDIR",
  "PS1",
  "PS2",
  "PS3",
  "PS4",
  "PWD",
  "RANDOM",
  "SECONDS",
  "SHELL",
  "TERM",
  "TERMCAP",
  "TERMINFO",
  "TMPDIR",
  "TZ",
  "USER",
  "VISUAL",
  "YACC",
  "YFLAGS",
].freeze
VAR_NAME_RE =

Regular expression mathcing strict and portable ENV var name rules: only ‘A-Z`, `0-9` and `_`; can not start with digit.

Returns:

  • (RegExp) 
/\A[A-Z_][A-Z0-9_]+\z/

Class Method Summary collapse

Class Method Details

.var_name?(name) ⇒ Boolean

Is ENV var name?

Must be String and match VAR_NAME_RE.

Parameters:

  • name (Object) —

    The name. No chance of ‘true` unless it’s a String.

Returns:

  • (Boolean) —

    ‘true` if it passes our mustard.



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# File 'lib/nrser/sys/env.rb', line 147

def self.var_name? name
  String === name && VAR_NAME_RE =~ name
end

.varize(string, prohibit_common_exports: false) ⇒ nil, String

Attempt to munge any string into a decent-looking and legal ENV var name.

We follow a strict, very portable (should be find in ‘sh`) guideline:

> Environment variable names […] consist solely of uppercase letters, > digits, and the ‘_’ (underscore) […] and do not begin with a digit.

Parameters:

  • string (String) —

    Take a guess.

Returns:

  • (nil) —

    If we didn’t end up with a legal ENV var name.

  • (String) —

    If we were able to munge a legal ENV var name.

See Also:



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# File 'lib/nrser/sys/env.rb', line 171

def self.varize string, prohibit_common_exports: false
  candidate = string.
    # 1.  Use {ActiveSupport}'s {String#underscore} to produce a nicely
    #     underscore-separated name for common strings like class names.
    underscore.
    # 2.  Convert lower-case letters to upper case.
    upcase.
    # 3.  Smush all contiguous runs of anything not `A-Z0-9` into a `_`.
    gsub( /[^A-Z0-9]+/, '_' ).
    # 4.  Bite off any leading digits.
    sub( /\A\d+/, '' ).
    # 5.  Chomp off any trailing `_`. Just for good looks :)
    chomp( '_' )
  
  # Return `nil` if we didn't get a legal ENV var name
  return nil unless var_name?( candidate )

  # If `prohibit_common_exports` is `true` and the name we made is in 
  # that list then return `nil`.
  if prohibit_common_exports && COMMON_EXPORT_NAMES.include?( candidate )
    return nil
  end

  # If we got here, we're good!
  return candidate
end