mcsee · October 5, 2025 18:39 · Oct 5, 2025 · Oct 5, 2025 · Oct 5, 2025 · Oct 5, 2025
diff --git a/reified.ts b/reified.ts
@@ -1,7 +1,7 @@
 // 2. Create a meaningful entity to group them  
 
 class PriceRange {
-  constructor(public min: currency, public max: currency) {
+  constructor(public min: Currency, public max: Currency) {
     if (min > max) {
       throw new Error(
         `Invalid price range: min (${min}) `+
@@ -17,7 +17,7 @@ class PriceRange {
 
 class Interval {
   // 3. Add missing validation rules to fail-fast
-  constructor(public start: date, public end: date) {
+  constructor(public start: Date, public end: Date) {
     if (start > end) {
       throw new Error(
         `Invalid date range: start (${start.toISOString()})  ` + 

diff --git a/reified.ts b/reified.ts
@@ -16,7 +16,7 @@ class PriceRange {
 }
 
 class Interval {
-  // 3. Add missing validation rules to fail fast
+  // 3. Add missing validation rules to fail-fast
   constructor(public start: date, public end: date) {
     if (start > end) {
       throw new Error(

diff --git a/reified.ts b/reified.ts
@@ -4,11 +4,13 @@ class PriceRange {
   constructor(public min: currency, public max: currency) {
     if (min > max) {
       throw new Error(
-        `Invalid price range: min (${min}) cannot be greater than max (${max})`
+        `Invalid price range: min (${min}) `+
+        `cannot be greater than max (${max})`
       );
     }
     if (min < 0) {
-      throw new Error(`Invalid price range: min (${min}) cannot be negative`);
+      throw new Error(
+        `Invalid price range: min (${min}) cannot be negative`);
     }
   }
 }

diff --git a/reified.ts b/reified.ts
@@ -18,7 +18,8 @@ class Interval {
   constructor(public start: date, public end: date) {
     if (start > end) {
       throw new Error(
-        `Invalid date range: start (${start.toISOString()}) cannot be after end (${end.toISOString()})`
+        `Invalid date range: start (${start.toISOString()})  ` + 
+        `cannot be after end (${end.toISOString()})`
       );
     }
   }

diff --git a/reified.ts b/reified.ts
@@ -1,3 +1,5 @@
+// 2. Create a meaningful entity to group them  
+
 class PriceRange {
   constructor(public min: currency, public max: currency) {
     if (min > max) {
@@ -11,7 +13,8 @@ class PriceRange {
   }
 }
 
-class DateRange {
+class Interval {
+  // 3. Add missing validation rules to fail fast
   constructor(public start: date, public end: date) {
     if (start > end) {
       throw new Error(
@@ -24,27 +27,29 @@ class DateRange {
 class HolidaySearchCriteria {
   constructor(
     public priceRange: PriceRange,
-    public dateRange: DateRange,
-    public destination?: string
+    public dateRange: Interval
   ) {}
 }
 
 function findHolidays(criteria: HolidaySearchCriteria): Holiday[] {
+  // 1. Identify multiple parameters of the same type  
   // No need to call validate() - already validated in constructors
+  // 4. Replace function signatures with the new entity  
   const { priceRange, dateRange } = criteria;
+  // 5. Adjust all callers to pass the entity  
+  // 6. Add context-specific names to improve clarity 
 
   return database.query({
     price: { $gte: priceRange.min, $lte: priceRange.max },
     startDate: { $gte: dateRange.start },
     endDate: { $lte: dateRange.end }
   });
 }
-
-// Usage - validation happens automatically
+
 try {
   const criteria = new HolidaySearchCriteria(
     new PriceRange(500, 1000),  // ✅ Valid
-    new DateRange(
+    new Inteval(
       new Date('2025-06-01'), 
       new Date('2025-06-15')
     )
@@ -53,6 +58,7 @@ try {
   findHolidays(criteria);
 
   // ❌ This will throw immediately
+  // Great for UI and API validation
   new PriceRange(1000, 500);
 
 } catch (error) {

diff --git a/reified.ts b/reified.ts
@@ -0,0 +1,60 @@
+class PriceRange {
+  constructor(public min: currency, public max: currency) {
+    if (min > max) {
+      throw new Error(
+        `Invalid price range: min (${min}) cannot be greater than max (${max})`
+      );
+    }
+    if (min < 0) {
+      throw new Error(`Invalid price range: min (${min}) cannot be negative`);
+    }
+  }
+}
+
+class DateRange {
+  constructor(public start: date, public end: date) {
+    if (start > end) {
+      throw new Error(
+        `Invalid date range: start (${start.toISOString()}) cannot be after end (${end.toISOString()})`
+      );
+    }
+  }
+}
+
+class HolidaySearchCriteria {
+  constructor(
+    public priceRange: PriceRange,
+    public dateRange: DateRange,
+    public destination?: string
+  ) {}
+}
+
+function findHolidays(criteria: HolidaySearchCriteria): Holiday[] {
+  // No need to call validate() - already validated in constructors
+  const { priceRange, dateRange } = criteria;
+
+  return database.query({
+    price: { $gte: priceRange.min, $lte: priceRange.max },
+    startDate: { $gte: dateRange.start },
+    endDate: { $lte: dateRange.end }
+  });
+}
+
+// Usage - validation happens automatically
+try {
+  const criteria = new HolidaySearchCriteria(
+    new PriceRange(500, 1000),  // ✅ Valid
+    new DateRange(
+      new Date('2025-06-01'), 
+      new Date('2025-06-15')
+    )
+  );
+
+  findHolidays(criteria);
+
+  // ❌ This will throw immediately
+  new PriceRange(1000, 500);
+
+} catch (error) {
+  console.error(error.message);
+}
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