Difference between revisions of "EDT:EGL Language Primitive Type Conversions"

Revision as of 12:50, 7 July 2011

Please see the parent of this page, EDT:EGL_Language.

Conversions Between Primitive Types (Table 4)

Conversion Matrix

To see if there's a conversion from one type to another, find the cell in "from" type's row and the "to" type's column.

Key

blank cell = The types are incompatible.  Conversion is not supported.

a = Same types (not a conversion).

b = Booleans convert to strings as "true" or "false" (lowercase).

c = Strings convert to/from timestamps using a predefined format for timestamps (to be defined later), the required fields come from the timestamp's pattern.   The conversions are not controlled by variables like RBD's defaultTimestampFormat.  Because of this, we can't convert from a string to a timestamp with no pattern.  We can convert from a timestamp with no pattern to a string.  Functions will be provided which convert to/from strings and timestamps with a format string supplied by the program.

d = Strings convert to/from numbers using our literal syntax for numbers.  The conversions are not controlled by variables like RBD's defaultNumericFormat.  Functions will be provided which convert to/from strings and numbers with a format string supplied by the program.

e = Strings convert to bytes using the bit pattern of the Unicode characters in the string.

f = All numeric types are compatible with each other, but some conversions can result in overflow or truncation.

g = Numeric types convert to/from bytes using the number's bit pattern. When the bytes type includes a size (i.e. "bytes(4)" not just "bytes") the conversion is legal only if the size of the number in bytes equals the length of the bytes type.

Notes on Table 4

1. We'll document error conditions of conversions, and their resulting exceptions. Whenever possible this documentation will be comments in the EGL source file for a type.