Make price/conf fields private with public unchecked accessor (#26)

* Make price/conf fields private with public unchecked accessor

Author: ali-behjati

pyth-sdk-solana/src/state.rs

@@ -16,8 +16,8 @@ use solana_program::pubkey::Pubkey;
 use std::mem::size_of;
 
 pub use pyth_sdk::{
-    PriceFeed,
     Price,
+    PriceFeed,
     PriceStatus,
 };
 
@@ -345,18 +345,18 @@ impl PriceAccount {
             status = PriceStatus::Unknown;
         }
 
-        PriceFeed {
-            id: price_key.to_bytes(),
-            price: self.agg.price,
-            conf: self.agg.conf,
+        PriceFeed::new(
+            price_key.to_bytes(),
             status,
-            max_num_publishers: self.num,
-            num_publishers: self.num_qt,
-            ema_price: self.ema_price.val,
-            ema_conf: self.ema_conf.val as u64,
-            expo: self.expo,
-            product_id: self.prod.val,
-        }
+            self.expo,
+            self.num,
+            self.num_qt,
+            self.prod.val,
+            self.agg.price,
+            self.agg.conf,
+            self.ema_price.val,
+            self.ema_conf.val as u64,
+        )
     }
 }
 

pyth-sdk/src/lib.rs

@@ -64,10 +64,6 @@ impl Default for PriceStatus {
 pub struct PriceFeed {
     /// Unique identifier for this price.
     pub id:                 PriceIdentifier,
-    /// The current price.
-    pub price:              i64,
-    /// Confidence interval around the price.
-    pub conf:               u64,
     /// Status of price (Trading is valid).
     pub status:             PriceStatus,
     /// Price exponent.
@@ -76,18 +72,49 @@ pub struct PriceFeed {
     pub max_num_publishers: u32,
     /// Number of publishers that made up current aggregate.
     pub num_publishers:     u32,
-    /// Exponentially moving average price.
-    pub ema_price:          i64,
-    /// Exponentially moving average confidence interval.
-    pub ema_conf:           u64,
     /// Product account key.
     pub product_id:         ProductIdentifier,
+    /// The current price.
+    price:                  i64,
+    /// Confidence interval around the price.
+    conf:                   u64,
+    /// Exponentially moving average price.
+    ema_price:              i64,
+    /// Exponentially moving average confidence interval.
+    ema_conf:               u64,    
 }
 
 impl PriceFeed {
+    /// Constructs a new Price Feed
+    pub fn new(
+        id: PriceIdentifier,
+        status: PriceStatus,
+        expo: i32,
+        max_num_publishers: u32,
+        num_publishers: u32,
+        product_id: ProductIdentifier,
+        price: i64,
+        conf: u64,
+        ema_price: i64,
+        ema_conf: u64,
+    ) -> PriceFeed {
+        PriceFeed {
+            id,
+            price,
+            conf,
+            status,
+            expo,
+            max_num_publishers,
+            num_publishers,
+            ema_price,
+            ema_conf,
+            product_id,
+        }
+    }
+
     /// Get the current price and confidence interval as fixed-point numbers of the form a *
     /// 10^e.
-    /// 
+    ///
     /// Returns a struct containing the current price, confidence interval, and the exponent for
     /// both numbers. Returns `None` if price information is currently unavailable for any
     /// reason.
@@ -103,9 +130,24 @@ impl PriceFeed {
         }
     }
 
+    /// Get the "unchecked" current price and confidence interval as fixed-point numbers of the form
+    /// a * 10^e.
+    ///
+    /// Returns a struct containing the current price, confidence interval, and the exponent for
+    /// both numbers. This method returns the price value without checking availability of the
+    /// price. This value might not be valid or updated when the price is not available.
+    /// Please use `get_current_price` where possible.
+    pub fn get_current_price_unchecked(&self) -> Price {
+        Price {
+            price: self.price,
+            conf:  self.conf,
+            expo:  self.expo,
+        }
+    }
+
     /// Get the exponential moving average price (ema_price) and a confidence interval on the
     /// result.
-    /// 
+    ///
     /// Returns `None` if the ema price is currently unavailable.
     /// At the moment, the confidence interval returned by this method is computed in
     /// a somewhat questionable way, so we do not recommend using it for high-value applications.
@@ -117,4 +159,22 @@ impl PriceFeed {
             expo:  self.expo,
         })
     }
+
+    /// Get the "unchecked" exponential moving average price (ema_price) and a confidence interval
+    /// on the result.
+    ///
+    /// Returns the price value without checking availability of the price.
+    /// This value might not be valid or updated when the price is not available.
+    /// Please use `get_ema_price` where possible.
+    ///
+    /// At the moment, the confidence interval returned by this method is computed in
+    /// a somewhat questionable way, so we do not recommend using it for high-value applications.
+    pub fn get_ema_price_unchecked(&self) -> Price {
+        // This method currently cannot return None, but may do so in the future.
+        Price {
+            price: self.ema_price,
+            conf:  self.ema_conf,
+            expo:  self.expo,
+        }
+    }
 }