1.10 Is Newer Than 1.9

1.10 Is Newer Than 1.9

The partner connector refuses any API older than a minimum version, and last night it refused every partner running release 1.10.0 while happily accepting 1.9.5. The gate is a single line of AL: exit(Actual >= Minimum) — a text comparison, which decides at the first differing character that '1' is smaller than '9' and stops reading. Versions are numbers separated by dots, not text, and AL has a data type for exactly that: Version. Your job is to make the gate compare versions as versions, accept the slightly messy strings partners actually send, and never crash on the garbage some of them send instead.

Requirements

Create a codeunit named "Version Compare" with two public procedures:

procedure Normalize(Input: Text): Text
procedure IsAtLeast(Actual: Text; Minimum: Text): Boolean

Rules:

1. A version is Major.Minor, Major.Minor.Build or Major.Minor.Build.Revision — two to four whole numbers separated by dots. Each part is a number, not text: 1.09 is major 1, minor 9.
2. The input may carry whitespace around it (spaces or tabs) and an optional leading v or V directly before the first digit, as in v1.10.0. Both are ignored.
3. Normalize returns the canonical four-part text Major.Minor.Build.Revision, with 0 written for every part the input did not supply and no leading zeros: 2.0 becomes 2.0.0.0, 1.10.0 becomes 1.10.0.0, 1.09.0 becomes 1.9.0.0, and 27.1.23456.26323 stays as it is.
4. Malformed input — anything that is not a version, such as 1.9.5-beta, abc, 1.2.3.4.5 (five parts) or an empty text — makes Normalize return an empty text. Never a runtime error.
5. IsAtLeast returns true when Actual is the same version as Minimum or a newer one, comparing the major part first, then minor, build and revision, each as a number. 1.10.0 is at least 1.9.5; 2.0 is at least 2.0.0 (they are the same version); 2.0.0 is at least 1.99.99.99; 1.9.5 is not at least 1.10.0. Both arguments get the same clean-up as in rule 2.
6. When either argument is malformed, IsAtLeast returns false — the connector refuses what it cannot read. Never a runtime error.

Pick object IDs in the 50100–50199 range, and reference other objects by name, never by ID.

The Version type, and its two traps

Version.Create(Text) parses a version text; Major(), Minor(), Build() and Revision() read the four parts; Version.Create(Integer, Integer, Integer, Integer) builds a version from numbers; ToText() writes one back as text; and two Version values compare with the ordinary relational operators (<, >=, =). Two things about it are not obvious:

• A part the input did not supply is not 0. Version.Create('2.0') remembers that Build and Revision were never given: they read back as -1 (the .NET convention underneath), ToText() gives 2.0 again, and the value compares below Version.Create('2.0.0'). So parsing both sides and comparing them straight away still gets rule 5 wrong. Rebuild the version from its four parts, writing 0 for any part below zero, before you compare or print it — and never pass a negative number to Create, it is rejected.
• Version.Create(Text) raises an error on malformed input; nothing returns false. Wrap the parse in a procedure marked [TryFunction]: it cannot declare a return value of its own, so hand the parsed version out through a var parameter, and use its Boolean — if TryParse(Input, Result) then. Called as a bare statement, a try function is an ordinary call and the error escapes.

For the clean-up, Text.Trim() removes surrounding whitespace including tabs (DelChr with ' ' removes spaces only), and Text.StartsWith plus CopyStr take care of the v.

What the tests check

The grading tests call Normalize with 2.0 (expecting 2.0.0.0), a generated three-part version (expecting a .0 appended) and a generated four-part version (expecting it unchanged), with 1.09.0 (expecting 1.9.0.0), with 1.10.0 wrapped in spaces and a tab, and with v1.10.0 and V2.5 — all exact text comparisons. They then expect an empty text, and no error, for 1.9.5-beta, abc, 1.2.3.4.5 and an empty text. IsAtLeast is called with 1.10.0 against 1.9.5 (expecting true) and the other way round (false), 2.0 against 2.0.0 (true), a generated four-part version against itself (true), against a minimum one revision higher (false) and one revision lower (true), a generated version with a non-zero revision against a minimum one build higher with revision 0 (false — the build is compared before the revision), 2.0.0 against 1.99.99.99 (true), and v1.10.0 against V1.10 (true). Finally 1.9.5-beta as the actual version and latest as the minimum must each return false — a runtime error raised by your code fails that test with the error text in the message.

Learn More

• Version data type — the two Create overloads and the Major/Minor/Build/Revision/ToText methods.
• Version.Create(Text) method — the accepted format, and the fact that anything else throws.
• Handling errors using try methods — how a [TryFunction] catches an error, and why its return value must be used.
• Text.Trim() method — removes leading and trailing whitespace of every kind.