Table of Contents

• 1. type
  • 1.1. Syntax
  • 1.2. Stack Effects
  • 1.3. Description
  • 1.4. PostScript Level
  • 1.5. Type Names
  • 1.6. Examples
  • 1.7. Common Use Cases
    • 1.7.1. Type Validation
    • 1.7.2. Generic Processing
    • 1.7.3. Debugging
  • 1.8. Common Pitfalls
  • 1.9. Error Conditions
  • 1.10. Implementation Notes
  • 1.11. Type Hierarchy
  • 1.12. See Also

1. type

Returns a name identifying the type of an object.

1.1. Syntax

any type → name

1.2. Stack Effects

Table 1. Before

Level	Object
0	any (any object)

Table 2. After

Level	Object
0	name (executable name identifying type)

1.3. Description

type returns a name object that identifies the type of its operand. The returned name has the executable attribute, making it convenient for type-dependent processing via dictionary lookup.

1.4. PostScript Level

Level 1 and later

1.5. Type Names

Object Type	Returned Name
Array	arraytype
Boolean	booleantype
Dictionary	dicttype
File	filetype
Font (fontID)	fonttype
Graphics state	gstatetype
Integer	integertype
Lock (DPS)	locktype
Mark	marktype
Name	nametype
Null	nulltype
Operator	operatortype
Packed array	packedarraytype
Real	realtype
Save object	savetype
String	stringtype
Condition (DPS)	conditiontype

1.6. Examples

Basic type checking

123 type         % Result: integertype
3.14 type        % Result: realtype
(text) type      % Result: stringtype
/name type       % Result: nametype
[1 2 3] type     % Result: arraytype

Type-dependent processing

5 dict begin
  /integertype { (Integer: ) print = } def
  /realtype { (Real: ) print = } def
  /stringtype { (String: ) print = } def

  42 dup type exec      % Prints "Integer: 42"
  3.14 dup type exec    % Prints "Real: 3.14"
end

Distinguishing arrays

[1 2 3] type /arraytype eq        % true
1 2 3 3 packedarray type /packedarraytype eq  % true

1.7. Common Use Cases

1.7.1. Type Validation

/validateNumber {
  dup type dup
  /integertype eq
  exch /realtype eq or not {
    /typecheck cvx exec
  } if
} def

1.7.2. Generic Processing

/typeHandlers 10 dict def
typeHandlers /integertype { handle-int } put
typeHandlers /stringtype { handle-str } put

/process {
  dup type typeHandlers exch get exec
} def

1.7.3. Debugging

/showtype {
  dup type 20 string cvs print
  ( : ) print =
} def

123 showtype         % Prints "integertype : 123"

1.8. Common Pitfalls

Font vs. Dictionary - A font dictionary returns dicttype, not fonttype. Only fontID objects return fonttype.

/Helvetica findfont type  % dicttype

Executable Name - The returned name is executable, which affects how it’s processed.

123 type          % Pushes executable 'integertype'
% If executed, looks up in dictionary

Future Types - The set of types may expand in future PostScript versions. Handle unknown types gracefully.

1.9. Error Conditions

Error	Condition
[stackunderflow]	No operand on stack

1.10. Implementation Notes

• Very fast operation (type stored with object)

• Returns executable name for dictionary-based dispatch

• Type names defined in systemdict

• Useful for polymorphic operators

1.11. Type Hierarchy

PostScript has no formal inheritance, but types can be categorized:

• Simple types: integer, real, boolean, null, mark

• Composite types: array, packedarray, string, dictionary

• Reference types: name, operator, save, gstate, font, file

• Synchronization (DPS): lock, condition

1.12. See Also

• cvlit - Convert to literal

• cvx - Convert to executable

• xcheck - Test if executable

• rcheck - Test if readable

• wcheck - Test if writable