Module: Tins::StringNamedPlaceholders

Defined in:
lib/tins/string_named_placeholders.rb

Overview

A module that provides methods for working with named placeholders in strings.

This module adds functionality to extract named placeholders from strings and assign values to them, making it easier to work with template-style strings that contain named substitution points.

Examples:

Extracting named placeholders from a string

"Hello %{name}, you have %{count} messages".named_placeholders
# => [:name, :count]

Assigning values to named placeholders

template = "Welcome %{user}, your balance is %{amount}"
template.named_placeholders_assign(user: "Alice", amount: "$100")
# => {:user=>"Alice", :amount=>"$100"}

Instance Method Summary collapse

Instance Method Details

#named_placeholders ⇒ Array<Symbol>

Returns an array of symbols representing the named placeholders found in the string.

This method scans the string for patterns matching named placeholders in the format %name and extracts the placeholder names, returning them as symbols in an array.

named placeholders found in the string.

Returns:

  • (Array<Symbol>) —

    An array of unique symbol representations of the



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# File 'lib/tins/string_named_placeholders.rb', line 26

def named_placeholders
  scan(/%\{([^}]+)\}/).inject([], &:concat).uniq.map(&:to_sym)
end

#named_placeholders_assign(hash, default: nil) ⇒ Hash

Assign values to named placeholders from a hash, using a default value for unspecified placeholders.

This method takes a hash of placeholder values and assigns them to the named placeholders found in the string. If a placeholder is not present in the input hash, the provided default value is used instead. The default can be a static value or a proc that receives the placeholder symbol as an argument.

placeholder.

Parameters:

  • hash (Hash) —

    A hash mapping placeholder names to their corresponding values.

  • default (Object, Proc) (defaults to: nil) —

    The default value to use for placeholders not present in the hash. If a proc is provided, it will be called with the placeholder symbol.

Returns:

  • (Hash) —

    A new hash containing the assigned values for each named



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# File 'lib/tins/string_named_placeholders.rb', line 45

def named_placeholders_assign(hash, default: nil)
  hash = hash.transform_keys(&:to_sym)
  named_placeholders.each_with_object({}) do |placeholder, h|
    h[placeholder] = hash[placeholder] ||
      (default.is_a?(Proc) ? default.(placeholder) : default)
  end
end

#named_placeholders_interpolate(hash, default: nil) ⇒ String

Interpolate named placeholders in the string with values from a hash.

This method takes a hash of placeholder values and substitutes the named placeholders found in the string with their corresponding values. Placeholders that are not present in the input hash will be replaced with the provided default value.

Parameters:

  • hash (Hash) —

    A hash mapping placeholder names to their corresponding values

  • default (Object, Proc) (defaults to: nil) —

    The default value to use for placeholders not present in the hash If a proc is provided, it will be called with the placeholder symbol

Returns:

  • (String) —

    A new string with named placeholders replaced by their values



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# File 'lib/tins/string_named_placeholders.rb', line 65

def named_placeholders_interpolate(hash, default: nil)
  values = named_placeholders_assign(hash, default:)
  self % values
end