factor out magic numbers into constants

Author: beepster4096

src/shims/windows/handle.rs

@@ -14,10 +14,12 @@ enum RealHandle {
 impl RealHandle {
     const USABLE_BITS: u32 = 31;
 
+    const THREAD_DISCRIMINANT: u32 = 1;
+
     fn discriminant(self) -> u32 {
         match self {
             // can't use zero here because all zero handle is invalid
-            Self::Thread(_) => 1,
+            Self::Thread(_) => Self::THREAD_DISCRIMINANT,
         }
     }
 
@@ -52,7 +54,7 @@ impl RealHandle {
 
     fn new(discriminant: u32, data: u32) -> Option<Self> {
         match discriminant {
-            1 => Some(Self::Thread(data.into())),
+            Self::THREAD_DISCRIMINANT => Some(Self::Thread(data.into())),
             _ => None,
         }
     }
@@ -88,10 +90,12 @@ pub enum Handle {
 }
 
 impl Handle {
+    const CURRENT_THREAD_VALUE: i32 = -7;
+
     fn to_packed(self) -> i32 {
         match self {
             Self::Null => 0,
-            Self::CurrentThread => -7,
+            Self::CurrentThread => Self::CURRENT_THREAD_VALUE,
             Self::Thread(thread) => RealHandle::Thread(thread).to_packed(),
         }
     }
@@ -107,7 +111,7 @@ impl Handle {
     fn from_packed(handle: i64) -> Option<Self> {
         if handle == 0 {
             Some(Self::Null)
-        } else if handle == -7 {
+        } else if handle == Self::CURRENT_THREAD_VALUE as i64 {
             Some(Self::CurrentThread)
         } else if let Ok(handle) = handle.try_into() {
             match RealHandle::from_packed(handle)? {