DiagramElements-FreezeValue/en

Introduction

The following describes the data format and syntax used in pin freeze values. In general, the text entered as freeze value is parsed by the input pin's datatype.

Integer

Integer constants can be entered in one of the following formats:

• decimal (for example: "1234" , "-1234)
• with Smalltalk radix prefix: (for example: "16rCAFE" , "16r-AA, "8r100, "2r101010000) any radix between 2 and 36 is allowed.
• with C radix prefix: (for example: "0xCAFE" , "-0xAA, "0b101010000) (0x for hex, 0o for octal, ob for binary).
  Notice that the C-octal notation (prefix 0) is not supported (ie. "0377" will be read as 377).

Float

• regular floats such as: "123.0", "+123.0", "-123.0", ".123", "123.", "123.0e+2", "123.0e-2"

String

If the pin's datatype is String, then no leading/trailing quotes are needed (actually: if there are quotes, these will be part of the string). However, quotes are needed if the type is not unambiguously a String type (i.e. Any or a Union type).

By default, NO C-style escape sequences are interpreted - i.e. the string is taken "as-is". If you want or need those, enable the "C-Escapes" toggle via the freeze-value's popup menu. You can then use the escapes:

• "\n" for a newline character
• "\r" for a return character
• "\t" for a tab
• "\b" for a backspace
• "\xXX" for a single byte hex-character code
• "\uXXXX" for a 32bit hex-character code
• "\\" for the "\" character.
• "\0" for a null character (null byte)

By default, variables of the form "$(xxx)" are expanded from either an expecco variable or the shell environment. Thus,

• "$(HOME)/foo/bar" will expand to the name of a subdirectory "foo/bar" under your home directory (in unix). Or if you have a variable named "HOME" in the expecco environment, to whatever that value is.

This behavior can be disabled via the freeze value's popup menu.

In addition, variables of the form "%(xxx)" are expanded by the value of the input pin named "xxx". This expansion is also controlled by a flag in the popup menu.

Freeze value expansion can be suppressed either in the basket itself (the freeze-menu), or globally via a flag in the project, to enforce backward compatibility of a whole library (in the rare situation, that an older library depends on such freeze values being unchanged).

Be reminded, that these variable expansions are only done for freeze values. If the value comes from another pin, it is passed unchanged.

Bytes (ByteArray)

Byte data can be entered in multiple forms:

• Smalltalk format: "#[ 1 2 3 ]" (spaces between byte values)
• JSON format: "[ 1, 2, 3 ]" (commas between byte values)
• C format: "{ 1, 2, 3 }" (braces and commas between byte values)
• hex format: "xxXXxxXX" (two hex characters per byte; no spaces in-between)
• hex format: "xx XX xx XX" (two hex characters per byte; with spaces in-between)

Any

To distinguish between strings and non-strings, String-constants for an Any-typed pin must be quoted. For example:

• "1234" - will be an integer value
• "1234.56" - will be an float value
• "'1234'" - will be a string value

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