1 files changed, 14 insertions, 14 deletions

diff --git a/apps/SoilMoistureIo.h b/apps/SoilMoistureIo.h
index 3e78f46..fac518c 100644
--- a/apps/SoilMoistureIo.h
+++ b/apps/SoilMoistureIo.h
@@ -169,21 +169,21 @@ public:
     }
 
     inline
-    vec::const_iterator begin() {
-        return values.begin();
+    vec::const_iterator cbegin() const {
+        return values.cbegin();
     }
 
     inline
-    vec::const_iterator end() {
-        return values.end();
+    vec::const_iterator cend() const {
+        return values.cend();
     }
 
     inline
-    bool empty() {
+    bool empty() const {
         return values.empty();
     }
 
-    o<string> at(const SampleKey *key) const {
+    const o<string> at(const SampleKey *key) const {
         SampleKeyIndex index = key->index;
         if (index >= values.size()) {
             return o<string>();
@@ -195,11 +195,11 @@ public:
     void set(const SampleKey *key, const std::string &value) {
         values.resize(max(values.size(), key->index + 1));
 
-        values.at(key->index) = o<string>(value);
+        values.at(key->index).reset(value);
     }
 
     template<class A>
-    const o<A> lexical_at(const SampleKey *key) {
+    const o<A> lexical_at(const SampleKey *key) const {
         auto value = at(key);
 
         if (!value) {
@@ -233,13 +233,13 @@ private:
 
 class SampleOutputStream {
 public:
-    virtual void write(SampleRecord sample) = 0;
+    virtual void write(SampleRecord const &sample) = 0;
 };
 
 class VectorSampleOutputStream : public SampleOutputStream {
 
 public:
-    virtual void write(SampleRecord sample) override;
+    virtual void write(SampleRecord const &sample) override;
 
 public:
     vector<SampleRecord> samples;
@@ -249,7 +249,7 @@ class CsvSampleOutputStream : public SampleOutputStream {
 public:
     CsvSampleOutputStream(shared_ptr<ostream> stream, KeyDictionary &dict);
 
-    void write(SampleRecord sample);
+    void write(SampleRecord const &sample);
 
     const KeyDictionary &getDict() {
         return dict;
@@ -267,7 +267,7 @@ class JsonSampleOutputStream : public SampleOutputStream {
 public:
     JsonSampleOutputStream(shared_ptr<ostream> stream, KeyDictionary &dict);
 
-    void write(SampleRecord sample) override;
+    void write(SampleRecord const &sample) override;
 
 private:
     KeyDictionary &dict;
@@ -278,7 +278,7 @@ class KeyValueSampleOutputStream : public SampleOutputStream {
 public:
     KeyValueSampleOutputStream(shared_ptr<ostream> stream, KeyDictionary &dict);
 
-    void write(SampleRecord sample) override;
+    void write(SampleRecord const &sample) override;
 
 private:
     KeyDictionary &dict;
@@ -289,7 +289,7 @@ class SqlSampleOutputStream : public SampleOutputStream {
 public:
     SqlSampleOutputStream(shared_ptr<ostream> stream, KeyDictionary &dict, string table_name);
 
-    void write(SampleRecord sample) override;
+    void write(SampleRecord const &sample) override;
 
 private:
     KeyDictionary &dict;