Fix issue #135: Implement lazy query initialization

[tamurashingo]

Problem

An error occurred when using the query macro before executing initialize-table-information.

This prevented pre-defining queries for performance optimization like this:

(defparameter *blog-query*
  (query <blog>
    :as :blog
    :columns ((blog :id :title))
    :where (:> (:blog :star) :min-star)))

Solution

Implemented lazy initialization using the placeholder pattern:

1. Introduction of <query-placeholder> class

   • When query macro is called before initialization, returns a placeholder instance
   • Placeholder has the same interface as the actual <query> instance

2. Initialization state management

   • *table-information-initialized*: Flag indicating whether initialization is complete
   • *query-initialization-callbacks*: List of callbacks to execute lazily

3. Transparent delegation

   • Placeholder delegates method calls like execute-query, generate-query, set-* to the actual <query>
   • Displays clear error message when used before initialization

Changes

Added

• src/environment.lisp: Added variables for initialization state management
• src/model/query.lisp: Added <query-placeholder> class and delegation methods
• test/model/query-lazy-initialization.lisp: Added tests for lazy initialization

Modified

• src/model/query.lisp: Modified query macro to behave based on initialization state
• src/model/query.lisp: Converted set-* functions to generic functions
• src/model/base-model.lisp: Modified initialize-table-information to execute callbacks

Usage Example

;; During application load (no error)
(defparameter *blog-query*
  (query <blog>
    :as :blog
    :columns ((blog :id :title))
    :where (:> (:blog :star) :min-star)))
;; => Returns <query-placeholder>

;; Attempting to use before initialization causes error
;; (execute-query *blog-query* '(:min-star 5))
;; => Error: "Query not initialized. Call initialize-table-information first."

;; Initialize
(initialize-table-information)
;; => Placeholder is converted to actual <query> instance

;; After initialization, works transparently
(execute-query *blog-query* '(:min-star 5))
;; => Works correctly

;; Queries defined after initialization return <query> instances immediately as before
(defparameter *user-query*
  (query <user>
    :as :user
    :columns ((user :id :name))))
;; => Returns <query> instance directly

Tests

Added 5 new tests (27 assertions):

• ✓ Placeholder is created before initialization
• ✓ Error occurs when used before initialization
• ✓ Actual query is created after initialization
• ✓ Placeholder works correctly after initialization
• ✓ Multiple placeholders are all initialized

All 63 existing tests also pass successfully.

Breaking Changes

None. Existing code works without changes.

Related Issue

Closes #135